diff --git a/app/Livewire/Admin/Maintenance.php b/app/Livewire/Admin/Maintenance.php
new file mode 100644
index 0000000..d591ae6
--- /dev/null
+++ b/app/Livewire/Admin/Maintenance.php
@@ -0,0 +1,162 @@
+<?php
+
+namespace App\Livewire\Admin;
+
+use App\Mail\MaintenanceAnnouncementMail;
+use App\Models\Datacenter;
+use App\Models\Host;
+use App\Models\MaintenanceNotification;
+use App\Models\MaintenanceWindow;
+use Illuminate\Support\Carbon;
+use Illuminate\Support\Facades\Mail;
+use Livewire\Attributes\Layout;
+use Livewire\Attributes\Validate;
+use Livewire\Component;
+
+#[Layout('layouts.admin')]
+class Maintenance extends Component
+{
+    #[Validate('required|string|max:255')]
+    public string $title = '';
+
+    #[Validate('nullable|string|max:2000')]
+    public string $publicDescription = '';
+
+    #[Validate('nullable|string|max:2000')]
+    public string $internalNotes = '';
+
+    #[Validate('required|date')]
+    public string $startsAt = '';
+
+    #[Validate('required|date')]
+    public string $endsAt = '';
+
+    /** @var array<int> */
+    public array $hostIds = [];
+
+    public function saveDraft(): void
+    {
+        $this->authorize('maintenance.manage');
+        $this->persist('draft');
+    }
+
+    public function publish(): void
+    {
+        $this->authorize('maintenance.manage');
+        $window = $this->persist('scheduled');
+        if ($window !== null) {
+            $this->sendAnnouncements($window);
+        }
+    }
+
+    private function persist(string $state): ?MaintenanceWindow
+    {
+        $data = $this->validate();
+
+        $starts = Carbon::parse($data['startsAt']);
+        $ends = Carbon::parse($data['endsAt']);
+
+        if ($ends->lessThanOrEqualTo($starts)) {
+            $this->addError('endsAt', __('maintenance.end_after_start'));
+
+            return null;
+        }
+        if ($state === 'scheduled') {
+            if (empty($this->hostIds)) {
+                $this->addError('hostIds', __('maintenance.need_host'));
+
+                return null;
+            }
+            if ($ends->isPast()) {
+                $this->addError('endsAt', __('maintenance.end_future'));
+
+                return null;
+            }
+        }
+
+        $window = MaintenanceWindow::create([
+            'title' => $data['title'],
+            'public_description' => $data['publicDescription'] ?: null,
+            'internal_notes' => $data['internalNotes'] ?: null,
+            'starts_at' => $starts,
+            'ends_at' => $ends,
+            'state' => $state,
+            'created_by' => auth()->id(),
+            'published_at' => $state === 'scheduled' ? now() : null,
+        ]);
+        $window->hosts()->sync(array_map('intval', $this->hostIds));
+
+        $this->reset('title', 'publicDescription', 'internalNotes', 'startsAt', 'endsAt', 'hostIds');
+        $this->dispatch('notify', message: __($state === 'scheduled' ? 'maintenance.published' : 'maintenance.draft_saved'));
+
+        return $window;
+    }
+
+    public function publishExisting(string $uuid): void
+    {
+        $this->authorize('maintenance.manage');
+        $window = MaintenanceWindow::query()->where('uuid', $uuid)->first();
+        if ($window === null || $window->state !== 'draft') {
+            return;
+        }
+        if ($window->hosts()->count() === 0 || $window->ends_at->isPast()) {
+            $this->dispatch('notify', message: __('maintenance.need_host'));
+
+            return;
+        }
+        $window->update(['state' => 'scheduled', 'published_at' => now()]);
+        $this->sendAnnouncements($window);
+        $this->dispatch('notify', message: __('maintenance.published'));
+    }
+
+    public function cancel(string $uuid): void
+    {
+        $this->authorize('maintenance.manage');
+        $window = MaintenanceWindow::query()->where('uuid', $uuid)->first();
+        if ($window === null || $window->state === 'cancelled') {
+            return;
+        }
+        $window->update(['state' => 'cancelled', 'cancelled_at' => now()]);
+        $this->dispatch('notify', message: __('maintenance.cancelled'));
+    }
+
+    /** Send the announcement to each affected customer exactly once (ledger-guarded). */
+    private function sendAnnouncements(MaintenanceWindow $window): void
+    {
+        foreach ($window->affectedCustomers() as $customer) {
+            $delivery = MaintenanceNotification::query()->firstOrCreate(
+                ['maintenance_window_id' => $window->id, 'customer_id' => $customer->id, 'event' => 'announcement'],
+                ['email' => $customer->email],
+            );
+            if ($delivery->wasRecentlyCreated) {
+                Mail::to($customer->email)->queue(new MaintenanceAnnouncementMail($window, $customer));
+                $delivery->update(['sent_at' => now()]);
+            }
+        }
+    }
+
+    public function render()
+    {
+        $windows = MaintenanceWindow::query()
+            ->withCount('hosts')
+            ->orderByDesc('starts_at')
+            ->get()
+            ->map(fn (MaintenanceWindow $w) => [
+                'uuid' => $w->uuid,
+                'title' => $w->title,
+                'starts_at' => $w->starts_at,
+                'ends_at' => $w->ends_at,
+                'state' => $w->derivedState(),
+                'hosts' => $w->hosts_count,
+                'affected' => $w->affectedCustomers()->count(),
+                'is_draft' => $w->state === 'draft',
+                'cancellable' => in_array($w->derivedState(), ['draft', 'upcoming', 'active'], true),
+            ]);
+
+        return view('livewire.admin.maintenance', [
+            'windows' => $windows,
+            'datacenters' => Datacenter::query()->orderBy('name')->get(),
+            'hosts' => Host::query()->orderBy('datacenter')->orderBy('name')->get(),
+        ]);
+    }
+}
diff --git a/app/Mail/MaintenanceAnnouncementMail.php b/app/Mail/MaintenanceAnnouncementMail.php
new file mode 100644
index 0000000..a9994d5
--- /dev/null
+++ b/app/Mail/MaintenanceAnnouncementMail.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Mail;
+
+use App\Models\Customer;
+use App\Models\MaintenanceWindow;
+use Illuminate\Bus\Queueable;
+use Illuminate\Contracts\Queue\ShouldQueue;
+use Illuminate\Mail\Mailable;
+use Illuminate\Mail\Mailables\Content;
+use Illuminate\Mail\Mailables\Envelope;
+use Illuminate\Queue\SerializesModels;
+
+class MaintenanceAnnouncementMail extends Mailable implements ShouldQueue
+{
+    use Queueable, SerializesModels;
+
+    public function __construct(
+        public MaintenanceWindow $window,
+        public Customer $customer,
+    ) {}
+
+    public function envelope(): Envelope
+    {
+        return new Envelope(subject: __('maintenance.mail_subject', ['title' => $this->window->title]));
+    }
+
+    public function content(): Content
+    {
+        return new Content(markdown: 'mail.maintenance-announcement', with: [
+            'title' => $this->window->title,
+            'description' => $this->window->public_description,
+            'startsAt' => $this->window->starts_at,
+            'endsAt' => $this->window->ends_at,
+            'name' => $this->customer->name,
+        ]);
+    }
+}
diff --git a/app/Models/Host.php b/app/Models/Host.php
index 2a29f52..b6019df 100644
--- a/app/Models/Host.php
+++ b/app/Models/Host.php
@@ -6,6 +6,7 @@ use App\Models\Concerns\HasUuid;
 use App\Provisioning\Contracts\ProvisioningSubject;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
 use Illuminate\Database\Eloquent\Relations\HasMany;
 use Illuminate\Database\Eloquent\Relations\MorphMany;
 
@@ -52,6 +53,11 @@ class Host extends Model implements ProvisioningSubject
         return $this->hasMany(Instance::class);
     }
 
+    public function maintenanceWindows(): BelongsToMany
+    {
+        return $this->belongsToMany(MaintenanceWindow::class);
+    }
+
     /** Free committable storage: total minus reserve. */
     public function freeGb(): int
     {
diff --git a/app/Models/MaintenanceNotification.php b/app/Models/MaintenanceNotification.php
new file mode 100644
index 0000000..1ea1802
--- /dev/null
+++ b/app/Models/MaintenanceNotification.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class MaintenanceNotification extends Model
+{
+    protected $fillable = ['maintenance_window_id', 'customer_id', 'event', 'email', 'sent_at'];
+
+    protected function casts(): array
+    {
+        return ['sent_at' => 'datetime'];
+    }
+}
diff --git a/app/Models/MaintenanceWindow.php b/app/Models/MaintenanceWindow.php
new file mode 100644
index 0000000..d1b7bd6
--- /dev/null
+++ b/app/Models/MaintenanceWindow.php
@@ -0,0 +1,110 @@
+<?php
+
+namespace App\Models;
+
+use App\Models\Concerns\HasUuid;
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Support\Collection;
+
+class MaintenanceWindow extends Model
+{
+    /** @use HasFactory<\Database\Factories\MaintenanceWindowFactory> */
+    use HasFactory, HasUuid;
+
+    /** How far before the start the banner appears (Codex: 72 h). */
+    public const DISPLAY_HOURS = 72;
+
+    protected $fillable = [
+        'title', 'public_description', 'internal_notes', 'starts_at', 'ends_at',
+        'state', 'created_by', 'published_at', 'cancelled_at', 'cancellation_reason',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'starts_at' => 'datetime',
+            'ends_at' => 'datetime',
+            'published_at' => 'datetime',
+            'cancelled_at' => 'datetime',
+        ];
+    }
+
+    public function hosts(): BelongsToMany
+    {
+        return $this->belongsToMany(Host::class);
+    }
+
+    public function deliveries(): HasMany
+    {
+        return $this->hasMany(MaintenanceNotification::class);
+    }
+
+    /** Derived lifecycle state — never stored (Codex). */
+    public function derivedState(): string
+    {
+        if ($this->state === 'cancelled') {
+            return 'cancelled';
+        }
+        if ($this->state === 'draft') {
+            return 'draft';
+        }
+        if (now()->lt($this->starts_at)) {
+            return 'upcoming';
+        }
+        if (now()->lte($this->ends_at)) {
+            return 'active';
+        }
+
+        return 'completed';
+    }
+
+    public function isPublished(): bool
+    {
+        return $this->state === 'scheduled';
+    }
+
+    /** Service-bearing customers on the assigned hosts (recomputed live). */
+    public function affectedCustomers(): Collection
+    {
+        $hostIds = $this->hosts()->pluck('hosts.id');
+        if ($hostIds->isEmpty()) {
+            return collect();
+        }
+
+        return Customer::query()
+            ->whereHas('instances', fn (Builder $q) => $q
+                ->whereIn('host_id', $hostIds)
+                ->whereIn('status', ['active', 'provisioning', 'cancellation_scheduled']))
+            ->get();
+    }
+
+    /**
+     * Scheduled windows to show a given customer right now: within the display
+     * horizon (72 h before start until the end) and touching one of the
+     * customer's service instances' hosts.
+     */
+    public static function bannerFor(Customer $customer): Collection
+    {
+        $hostIds = Instance::query()
+            ->where('customer_id', $customer->id)
+            ->whereIn('status', ['active', 'provisioning', 'cancellation_scheduled'])
+            ->whereNotNull('host_id')
+            ->pluck('host_id')->unique();
+
+        if ($hostIds->isEmpty()) {
+            return collect();
+        }
+
+        return self::query()
+            ->where('state', 'scheduled')
+            ->where('ends_at', '>=', now())
+            ->where('starts_at', '<=', now()->addHours(self::DISPLAY_HOURS))
+            ->whereHas('hosts', fn (Builder $q) => $q->whereIn('hosts.id', $hostIds))
+            ->orderBy('starts_at')
+            ->get();
+    }
+}
diff --git a/database/factories/MaintenanceWindowFactory.php b/database/factories/MaintenanceWindowFactory.php
new file mode 100644
index 0000000..4e38714
--- /dev/null
+++ b/database/factories/MaintenanceWindowFactory.php
@@ -0,0 +1,34 @@
+<?php
+
+namespace Database\Factories;
+
+use App\Models\MaintenanceWindow;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+/** @extends Factory<MaintenanceWindow> */
+class MaintenanceWindowFactory extends Factory
+{
+    protected $model = MaintenanceWindow::class;
+
+    public function definition(): array
+    {
+        return [
+            'title' => 'Netzwerk-Wartung '.$this->faker->city(),
+            'public_description' => 'Kurzzeitige Nichtverfügbarkeit möglich.',
+            'internal_notes' => null,
+            'starts_at' => now()->addDays(2),
+            'ends_at' => now()->addDays(2)->addHours(2),
+            'state' => 'draft',
+        ];
+    }
+
+    public function scheduled(): static
+    {
+        return $this->state(['state' => 'scheduled', 'published_at' => now()]);
+    }
+
+    public function active(): static
+    {
+        return $this->state(['state' => 'scheduled', 'published_at' => now(), 'starts_at' => now()->subHour(), 'ends_at' => now()->addHour()]);
+    }
+}
diff --git a/database/migrations/2026_07_25_140001_create_maintenance_windows.php b/database/migrations/2026_07_25_140001_create_maintenance_windows.php
new file mode 100644
index 0000000..1f4bd22
--- /dev/null
+++ b/database/migrations/2026_07_25_140001_create_maintenance_windows.php
@@ -0,0 +1,57 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * Maintenance windows: create once, assign to many hosts. Active/completed are
+ * DERIVED from state + starts_at/ends_at + now — never persisted as status.
+ */
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('maintenance_windows', function (Blueprint $table) {
+            $table->id();
+            $table->uuid('uuid')->unique();
+            $table->string('title');
+            $table->text('public_description')->nullable();
+            $table->text('internal_notes')->nullable();
+            $table->timestamp('starts_at');
+            $table->timestamp('ends_at');
+            $table->string('state')->default('draft'); // draft | scheduled | cancelled
+            $table->foreignId('created_by')->nullable()->constrained('users')->nullOnDelete();
+            $table->timestamp('published_at')->nullable();
+            $table->timestamp('cancelled_at')->nullable();
+            $table->string('cancellation_reason')->nullable();
+            $table->timestamps();
+        });
+
+        Schema::create('host_maintenance_window', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('host_id')->constrained()->cascadeOnDelete();
+            $table->foreignId('maintenance_window_id')->constrained()->cascadeOnDelete();
+            $table->unique(['host_id', 'maintenance_window_id']);
+        });
+
+        // Idempotent notification ledger — one row per (window, customer, event).
+        Schema::create('maintenance_notifications', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('maintenance_window_id')->constrained()->cascadeOnDelete();
+            $table->foreignId('customer_id')->constrained()->cascadeOnDelete();
+            $table->string('event'); // announcement | cancelled
+            $table->string('email');
+            $table->timestamp('sent_at')->nullable();
+            $table->timestamps();
+            $table->unique(['maintenance_window_id', 'customer_id', 'event'], 'mw_notif_unique');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('maintenance_notifications');
+        Schema::dropIfExists('host_maintenance_window');
+        Schema::dropIfExists('maintenance_windows');
+    }
+};
diff --git a/lang/de/admin.php b/lang/de/admin.php
index 551a08e..2dbc668 100644
--- a/lang/de/admin.php
+++ b/lang/de/admin.php
@@ -12,6 +12,7 @@ return [
         'hosts' => 'Hosts',
         'datacenters' => 'Rechenzentren',
         'provisioning' => 'Provisioning',
+        'maintenance' => 'Wartungen',
         'revenue' => 'Umsatz',
         'settings' => 'Einstellungen',
     ],
diff --git a/lang/de/maintenance.php b/lang/de/maintenance.php
new file mode 100644
index 0000000..e5e2f93
--- /dev/null
+++ b/lang/de/maintenance.php
@@ -0,0 +1,50 @@
+<?php
+
+return [
+    'title' => 'Wartungen',
+    'subtitle' => 'Wartungsfenster anlegen, mehreren Hosts zuweisen und betroffene Kunden benachrichtigen.',
+    'empty' => 'Noch keine Wartungsfenster.',
+
+    'col_window' => 'Fenster',
+    'col_when' => 'Zeitraum',
+    'col_impact' => 'Betroffen',
+    'col_state' => 'Status',
+    'col_actions' => 'Aktionen',
+    'impact' => ':hosts Host(s) · :customers Kunde(n)',
+
+    'state_draft' => 'Entwurf',
+    'state_upcoming' => 'Geplant',
+    'state_active' => 'Aktiv',
+    'state_completed' => 'Abgeschlossen',
+    'state_cancelled' => 'Storniert',
+
+    'new_title' => 'Neues Wartungsfenster',
+    'field_title' => 'Titel',
+    'field_public' => 'Beschreibung für Kunden',
+    'field_internal' => 'Interne Notizen',
+    'field_start' => 'Beginn',
+    'field_end' => 'Ende',
+    'field_hosts' => 'Betroffene Hosts',
+    'save_draft' => 'Als Entwurf speichern',
+    'publish' => 'Veröffentlichen',
+    'publish_notify' => 'Veröffentlichen & benachrichtigen',
+    'cancel' => 'Stornieren',
+    'mail_note' => 'Beim Veröffentlichen erhalten betroffene Kunden eine Ankündigungs-E-Mail (aktuell Log/Mock).',
+
+    'draft_saved' => 'Entwurf gespeichert.',
+    'published' => 'Wartung veröffentlicht — Kunden werden benachrichtigt.',
+    'cancelled' => 'Wartung storniert.',
+    'end_after_start' => 'Das Ende muss nach dem Beginn liegen.',
+    'end_future' => 'Das Ende muss in der Zukunft liegen.',
+    'need_host' => 'Bitte mindestens einen Host auswählen.',
+
+    'banner_upcoming' => 'Geplante Wartung von :start bis :end — es ist nichts zu tun.',
+    'banner_active' => 'Wartung läuft — Ihre Cloud ist ggf. vorübergehend nicht erreichbar. Voraussichtliches Ende: :end.',
+
+    'mail_subject' => 'Geplante Wartung: :title',
+    'mail_heading' => 'Geplante Wartung',
+    'mail_greeting' => 'Hallo :name,',
+    'mail_window' => 'Zeitraum: :start bis :end.',
+    'mail_no_action' => 'Es ist nichts zu tun. Ihre Daten bleiben sicher.',
+    'mail_signoff' => 'Viele Grüße',
+];
diff --git a/lang/en/admin.php b/lang/en/admin.php
index 598a48c..acdf864 100644
--- a/lang/en/admin.php
+++ b/lang/en/admin.php
@@ -12,6 +12,7 @@ return [
         'hosts' => 'Hosts',
         'datacenters' => 'Datacenters',
         'provisioning' => 'Provisioning',
+        'maintenance' => 'Maintenance',
         'revenue' => 'Revenue',
         'settings' => 'Settings',
     ],
diff --git a/lang/en/maintenance.php b/lang/en/maintenance.php
new file mode 100644
index 0000000..66b8e4b
--- /dev/null
+++ b/lang/en/maintenance.php
@@ -0,0 +1,50 @@
+<?php
+
+return [
+    'title' => 'Maintenance',
+    'subtitle' => 'Create maintenance windows, assign them to multiple hosts and notify affected customers.',
+    'empty' => 'No maintenance windows yet.',
+
+    'col_window' => 'Window',
+    'col_when' => 'When',
+    'col_impact' => 'Affected',
+    'col_state' => 'Status',
+    'col_actions' => 'Actions',
+    'impact' => ':hosts host(s) · :customers customer(s)',
+
+    'state_draft' => 'Draft',
+    'state_upcoming' => 'Scheduled',
+    'state_active' => 'Active',
+    'state_completed' => 'Completed',
+    'state_cancelled' => 'Cancelled',
+
+    'new_title' => 'New maintenance window',
+    'field_title' => 'Title',
+    'field_public' => 'Customer-facing description',
+    'field_internal' => 'Internal notes',
+    'field_start' => 'Start',
+    'field_end' => 'End',
+    'field_hosts' => 'Affected hosts',
+    'save_draft' => 'Save as draft',
+    'publish' => 'Publish',
+    'publish_notify' => 'Publish & notify',
+    'cancel' => 'Cancel',
+    'mail_note' => 'On publish, affected customers receive an announcement email (currently log/mock).',
+
+    'draft_saved' => 'Draft saved.',
+    'published' => 'Maintenance published — customers are being notified.',
+    'cancelled' => 'Maintenance cancelled.',
+    'end_after_start' => 'The end must be after the start.',
+    'end_future' => 'The end must be in the future.',
+    'need_host' => 'Please select at least one host.',
+
+    'banner_upcoming' => 'Scheduled maintenance from :start to :end — no action needed.',
+    'banner_active' => 'Maintenance in progress — your cloud may be temporarily unavailable. Expected end: :end.',
+
+    'mail_subject' => 'Scheduled maintenance: :title',
+    'mail_heading' => 'Scheduled maintenance',
+    'mail_greeting' => 'Hello :name,',
+    'mail_window' => 'Window: :start to :end.',
+    'mail_no_action' => 'No action is required. Your data stays safe.',
+    'mail_signoff' => 'Best regards',
+];
diff --git a/resources/views/layouts/admin.blade.php b/resources/views/layouts/admin.blade.php
index 127af70..381e0a5 100644
--- a/resources/views/layouts/admin.blade.php
+++ b/resources/views/layouts/admin.blade.php
@@ -35,6 +35,7 @@
                     ['admin.hosts', 'server', 'hosts'],
                     ['admin.datacenters', 'database', 'datacenters'],
                     ['admin.provisioning', 'activity', 'provisioning'],
+                    ['admin.maintenance', 'alert-triangle', 'maintenance'],
                     ['admin.revenue', 'trending-up', 'revenue'],
                 ] as [$route, $icon, $key])
                     <x-ui.nav-item :href="route($route)" :active="request()->routeIs($route)">
diff --git a/resources/views/layouts/portal-app.blade.php b/resources/views/layouts/portal-app.blade.php
index 1b63bd0..792238c 100644
--- a/resources/views/layouts/portal-app.blade.php
+++ b/resources/views/layouts/portal-app.blade.php
@@ -11,6 +11,28 @@
     @livewireStyles
 </head>
 <body class="min-h-full bg-bg text-body antialiased" x-data="{ nav: false }">
+    @php
+        $maintenanceWindows = collect();
+        if (auth()->check()) {
+            $portalCustomer = \App\Models\Customer::query()->where('user_id', auth()->id())->first()
+                ?? \App\Models\Customer::query()->where('email', auth()->user()->email)->first();
+            if ($portalCustomer) {
+                $maintenanceWindows = \App\Models\MaintenanceWindow::bannerFor($portalCustomer);
+            }
+        }
+    @endphp
+    @foreach ($maintenanceWindows as $mw)
+        @php $isActive = now()->greaterThanOrEqualTo($mw->starts_at) && now()->lessThanOrEqualTo($mw->ends_at); @endphp
+        <div class="flex flex-wrap items-center justify-center gap-x-3 gap-y-1 border-b {{ $isActive ? 'border-warning-border bg-warning-bg' : 'border-info-border bg-info-bg' }} px-4 py-2 text-center text-sm text-ink">
+            <x-ui.icon name="alert-triangle" class="size-4 shrink-0 {{ $isActive ? 'text-warning' : 'text-info' }}" />
+            <span class="font-medium">{{ $mw->title }}</span>
+            <span class="text-muted">
+                {{ $isActive
+                    ? __('maintenance.banner_active', ['end' => $mw->ends_at->isoFormat('LT')])
+                    : __('maintenance.banner_upcoming', ['start' => $mw->starts_at->isoFormat('LLL'), 'end' => $mw->ends_at->isoFormat('LT')]) }}
+            </span>
+        </div>
+    @endforeach
     @if (session('impersonator_id'))
         {{-- Admin impersonation banner — visible on every portal page until the admin returns. --}}
         <div class="flex flex-wrap items-center justify-center gap-x-3 gap-y-1 border-b border-warning-border bg-warning-bg px-4 py-2 text-center text-sm font-medium text-ink">
diff --git a/resources/views/livewire/admin/maintenance.blade.php b/resources/views/livewire/admin/maintenance.blade.php
new file mode 100644
index 0000000..037a4db
--- /dev/null
+++ b/resources/views/livewire/admin/maintenance.blade.php
@@ -0,0 +1,105 @@
+<div class="space-y-6">
+    <div class="animate-rise">
+        <h1 class="text-2xl font-semibold tracking-tight text-ink">{{ __('maintenance.title') }}</h1>
+        <p class="mt-1 text-sm text-muted">{{ __('maintenance.subtitle') }}</p>
+    </div>
+
+    <div class="grid grid-cols-1 gap-6 lg:grid-cols-[1fr_340px] lg:items-start">
+        {{-- Windows list --}}
+        <div class="overflow-hidden rounded-xl border border-line bg-surface shadow-xs animate-rise [animation-delay:60ms]">
+            @if ($windows->isEmpty())
+                <p class="p-8 text-center text-sm text-muted">{{ __('maintenance.empty') }}</p>
+            @else
+                <div class="overflow-x-auto">
+                    <table class="w-full text-sm">
+                        <thead>
+                            <tr class="border-b border-line bg-surface-2 text-left text-xs uppercase tracking-wide text-faint">
+                                <th class="px-4 py-3 font-semibold">{{ __('maintenance.col_window') }}</th>
+                                <th class="px-4 py-3 font-semibold">{{ __('maintenance.col_when') }}</th>
+                                <th class="px-4 py-3 font-semibold">{{ __('maintenance.col_impact') }}</th>
+                                <th class="px-4 py-3 font-semibold">{{ __('maintenance.col_state') }}</th>
+                                <th class="px-4 py-3 text-right font-semibold">{{ __('maintenance.col_actions') }}</th>
+                            </tr>
+                        </thead>
+                        <tbody>
+                            @foreach ($windows as $w)
+                                @php $tone = ['draft' => 'info', 'upcoming' => 'provisioning', 'active' => 'warning', 'completed' => 'active', 'cancelled' => 'suspended'][$w['state']] ?? 'info'; @endphp
+                                <tr wire:key="mw-{{ $w['uuid'] }}" class="border-b border-line last:border-0 hover:bg-surface-hover">
+                                    <td class="px-4 py-3 font-medium text-ink">{{ $w['title'] }}</td>
+                                    <td class="px-4 py-3 text-xs text-body">{{ $w['starts_at']->isoFormat('DD.MM. HH:mm') }} – {{ $w['ends_at']->isoFormat('HH:mm') }}</td>
+                                    <td class="px-4 py-3 font-mono text-xs text-muted">{{ __('maintenance.impact', ['hosts' => $w['hosts'], 'customers' => $w['affected']]) }}</td>
+                                    <td class="px-4 py-3"><x-ui.badge :status="$tone">{{ __('maintenance.state_'.$w['state']) }}</x-ui.badge></td>
+                                    <td class="px-4 py-3 text-right">
+                                        <div class="inline-flex gap-1.5">
+                                            @if ($w['is_draft'])
+                                                <button type="button" wire:click="publishExisting('{{ $w['uuid'] }}')" class="rounded-md border border-line px-2.5 py-1.5 text-xs font-semibold text-body hover:border-accent-border hover:text-accent-text">{{ __('maintenance.publish') }}</button>
+                                            @endif
+                                            @if ($w['cancellable'])
+                                                <button type="button" wire:click="cancel('{{ $w['uuid'] }}')" class="rounded-md border border-line px-2.5 py-1.5 text-xs font-semibold text-muted hover:border-danger hover:text-danger">{{ __('maintenance.cancel') }}</button>
+                                            @endif
+                                        </div>
+                                    </td>
+                                </tr>
+                            @endforeach
+                        </tbody>
+                    </table>
+                </div>
+            @endif
+        </div>
+
+        {{-- Create form --}}
+        <form wire:submit="publish" class="space-y-4 rounded-xl border border-line bg-surface p-5 shadow-xs animate-rise [animation-delay:120ms]">
+            <h2 class="font-semibold text-ink">{{ __('maintenance.new_title') }}</h2>
+            <x-ui.input name="title" wire:model="title" :label="__('maintenance.field_title')" />
+            <div>
+                <label class="text-sm font-medium text-body" for="publicDescription">{{ __('maintenance.field_public') }}</label>
+                <textarea id="publicDescription" wire:model="publicDescription" rows="2" class="mt-1.5 w-full rounded-md border border-line-strong bg-surface px-3 py-2 text-sm text-ink"></textarea>
+            </div>
+            <div>
+                <label class="text-sm font-medium text-body" for="internalNotes">{{ __('maintenance.field_internal') }}</label>
+                <textarea id="internalNotes" wire:model="internalNotes" rows="2" class="mt-1.5 w-full rounded-md border border-line-strong bg-surface px-3 py-2 text-sm text-ink"></textarea>
+            </div>
+            <div class="grid grid-cols-1 gap-3 sm:grid-cols-2">
+                <div>
+                    <label class="text-sm font-medium text-body" for="startsAt">{{ __('maintenance.field_start') }}</label>
+                    <input id="startsAt" type="datetime-local" wire:model="startsAt" class="mt-1.5 w-full rounded-md border border-line-strong bg-surface px-3 py-2 text-sm text-ink" />
+                    @error('startsAt')<p class="mt-1 text-xs text-danger">{{ $message }}</p>@enderror
+                </div>
+                <div>
+                    <label class="text-sm font-medium text-body" for="endsAt">{{ __('maintenance.field_end') }}</label>
+                    <input id="endsAt" type="datetime-local" wire:model="endsAt" class="mt-1.5 w-full rounded-md border border-line-strong bg-surface px-3 py-2 text-sm text-ink" />
+                    @error('endsAt')<p class="mt-1 text-xs text-danger">{{ $message }}</p>@enderror
+                </div>
+            </div>
+
+            <div>
+                <p class="text-sm font-medium text-body">{{ __('maintenance.field_hosts') }}</p>
+                @error('hostIds')<p class="mt-1 text-xs text-danger">{{ $message }}</p>@enderror
+                <div class="mt-1.5 max-h-48 space-y-3 overflow-y-auto rounded-md border border-line p-3">
+                    @foreach ($datacenters as $dc)
+                        @php $dcHosts = $hosts->where('datacenter', $dc->code); @endphp
+                        @if ($dcHosts->isNotEmpty())
+                            <div>
+                                <p class="text-xs font-semibold uppercase tracking-wide text-faint">{{ $dc->name }}</p>
+                                <div class="mt-1 space-y-1">
+                                    @foreach ($dcHosts as $host)
+                                        <label class="flex items-center gap-2 text-sm text-body">
+                                            <input type="checkbox" wire:model="hostIds" value="{{ $host->id }}" class="rounded border-line-strong text-accent-active" />
+                                            <span class="font-mono">{{ $host->name }}</span>
+                                        </label>
+                                    @endforeach
+                                </div>
+                            </div>
+                        @endif
+                    @endforeach
+                </div>
+            </div>
+
+            <div class="flex flex-wrap justify-end gap-2">
+                <x-ui.button variant="secondary" type="button" wire:click="saveDraft" wire:loading.attr="disabled" wire:target="saveDraft">{{ __('maintenance.save_draft') }}</x-ui.button>
+                <x-ui.button variant="primary" type="submit" wire:loading.attr="disabled" wire:target="publish">{{ __('maintenance.publish_notify') }}</x-ui.button>
+            </div>
+            <p class="text-xs text-faint">{{ __('maintenance.mail_note') }}</p>
+        </form>
+    </div>
+</div>
diff --git a/resources/views/mail/maintenance-announcement.blade.php b/resources/views/mail/maintenance-announcement.blade.php
new file mode 100644
index 0000000..258cec8
--- /dev/null
+++ b/resources/views/mail/maintenance-announcement.blade.php
@@ -0,0 +1,18 @@
+<x-mail::message>
+# {{ __('maintenance.mail_heading') }}
+
+{{ __('maintenance.mail_greeting', ['name' => $name]) }}
+
+**{{ $title }}**
+
+{{ __('maintenance.mail_window', ['start' => $startsAt->isoFormat('LLLL'), 'end' => $endsAt->isoFormat('LLLL')]) }}
+
+@if ($description)
+{{ $description }}
+@endif
+
+{{ __('maintenance.mail_no_action') }}
+
+{{ __('maintenance.mail_signoff') }}<br>
+{{ config('app.name') }}
+</x-mail::message>
diff --git a/routes/web.php b/routes/web.php
index 4774cbc..6dfaeb6 100644
--- a/routes/web.php
+++ b/routes/web.php
@@ -63,6 +63,7 @@ Route::middleware(['auth', 'admin'])->prefix('admin')->name('admin.')->group(fun
     // POST so the identity change is CSRF-protected (a GET could be forced cross-site).
     Route::post('/impersonate/{customer}', [ImpersonationController::class, 'start'])->name('impersonate');
     Route::get('/provisioning', Admin\Provisioning::class)->name('provisioning');
+    Route::get('/maintenance', Admin\Maintenance::class)->name('maintenance');
     Route::get('/revenue', Admin\Revenue::class)->name('revenue');
     Route::get('/settings', Admin\Settings::class)->name('settings');
 });
diff --git a/tests/Feature/Admin/MaintenanceTest.php b/tests/Feature/Admin/MaintenanceTest.php
new file mode 100644
index 0000000..1f68eb0
--- /dev/null
+++ b/tests/Feature/Admin/MaintenanceTest.php
@@ -0,0 +1,75 @@
+<?php
+
+use App\Livewire\Admin\Maintenance;
+use App\Mail\MaintenanceAnnouncementMail;
+use App\Models\Customer;
+use App\Models\Host;
+use App\Models\Instance;
+use App\Models\MaintenanceNotification;
+use App\Models\MaintenanceWindow;
+use Illuminate\Support\Facades\Mail;
+use Livewire\Livewire;
+
+// operator() helper defined in RbacTest.
+
+function affectedCustomerOn(Host $host): Customer
+{
+    $customer = Customer::factory()->create();
+    Instance::factory()->create(['customer_id' => $customer->id, 'host_id' => $host->id, 'status' => 'active']);
+
+    return $customer;
+}
+
+it('publishes a window and emails affected customers once (idempotent)', function () {
+    Mail::fake();
+    $host = Host::factory()->active()->create();
+    $customer = affectedCustomerOn($host);
+
+    Livewire::actingAs(operator('Owner'))->test(Maintenance::class)
+        ->set('title', 'Netz-Wartung')
+        ->set('startsAt', now()->addDay()->format('Y-m-d\TH:i'))
+        ->set('endsAt', now()->addDay()->addHours(2)->format('Y-m-d\TH:i'))
+        ->set('hostIds', [$host->id])
+        ->call('publish')->assertHasNoErrors();
+
+    $window = MaintenanceWindow::query()->where('title', 'Netz-Wartung')->first();
+    expect($window)->not->toBeNull()->and($window->state)->toBe('scheduled')
+        ->and($window->hosts()->count())->toBe(1);
+    Mail::assertQueued(MaintenanceAnnouncementMail::class, 1);
+    expect(MaintenanceNotification::query()->where('customer_id', $customer->id)->count())->toBe(1);
+
+    // The ledger's unique (window, customer, event) makes re-announcing a no-op.
+    expect(fn () => MaintenanceNotification::query()->create([
+        'maintenance_window_id' => $window->id, 'customer_id' => $customer->id, 'event' => 'announcement', 'email' => $customer->email,
+    ]))->toThrow(Illuminate\Database\UniqueConstraintViolationException::class);
+});
+
+it('requires a host to publish', function () {
+    Livewire::actingAs(operator('Owner'))->test(Maintenance::class)
+        ->set('title', 'X')
+        ->set('startsAt', now()->addDay()->format('Y-m-d\TH:i'))
+        ->set('endsAt', now()->addDay()->addHours(2)->format('Y-m-d\TH:i'))
+        ->set('hostIds', [])
+        ->call('publish')->assertHasErrors(['hostIds']);
+});
+
+it('forbids non-privileged roles from managing maintenance', function () {
+    Livewire::actingAs(operator('Support'))->test(Maintenance::class)
+        ->set('title', 'X')->set('startsAt', now()->addDay()->format('Y-m-d\TH:i'))
+        ->set('endsAt', now()->addDay()->addHours(2)->format('Y-m-d\TH:i'))
+        ->call('saveDraft')->assertForbidden();
+});
+
+it('shows the banner to an affected customer within the horizon', function () {
+    $host = Host::factory()->active()->create();
+    $customer = affectedCustomerOn($host);
+    $window = MaintenanceWindow::factory()->scheduled()->create(['starts_at' => now()->addDay(), 'ends_at' => now()->addDay()->addHour()]);
+    $window->hosts()->attach($host->id);
+
+    $banner = MaintenanceWindow::bannerFor($customer);
+    expect($banner)->toHaveCount(1)->and($banner->first()->id)->toBe($window->id);
+
+    // A customer on another host sees nothing.
+    $other = affectedCustomerOn(Host::factory()->active()->create());
+    expect(MaintenanceWindow::bannerFor($other))->toHaveCount(0);
+});