diff --git a/README.md b/README.md
index 9832e16..e35af89 100644
--- a/README.md
+++ b/README.md
@@ -82,6 +82,55 @@ Das Projekt ist für den Betrieb mit Docker optimiert.
    - URL: `/admin`
    - Standard-Passwort: `admin123` (Bitte in `docker-compose.yml` ändern!)
 
+## Nginx-Konfiguration (für Reverse Proxy)
+
+Wenn du Nginx als Reverse Proxy verwendest, benötigst du spezielle Einstellungen für Audio-Streaming:
+
+```nginx
+server {
+    listen 80;
+    server_name your-domain.com;
+
+    # Erhöhe Upload-Limit
+    client_max_body_size 50M;
+
+    location / {
+        proxy_pass http://localhost:3010;
+        proxy_http_version 1.1;
+        
+        # Wichtig für Audio-Streaming: Range Requests weiterleiten
+        proxy_set_header Range $http_range;
+        proxy_set_header If-Range $http_if_range;
+        proxy_no_cache $http_range $http_if_range;
+        
+        # Standard Proxy Headers
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+    }
+}
+```
+
+Eine vollständige Beispiel-Konfiguration findest du in `nginx.conf.example`.
+
+## Troubleshooting
+
+### Audio-Dateien lassen sich nicht abspielen (in Produktion mit Nginx)
+
+**Problem:** MP3-Dateien funktionieren lokal, aber nicht hinter Nginx.
+
+**Lösung:**
+1. Stelle sicher, dass Nginx Range Requests unterstützt (siehe Nginx-Konfiguration oben)
+2. Prüfe die Nginx-Logs: `sudo tail -f /var/log/nginx/error.log`
+3. Teste direkt ohne Nginx: `http://localhost:3010/uploads/dateiname.mp3`
+4. Überprüfe die Response-Headers im Browser (Developer Tools → Network)
+
+**Wichtige Nginx-Einstellungen:**
+- `proxy_set_header Range $http_range;` - Leitet Range Requests weiter
+- `proxy_buffering off;` - Deaktiviert Buffering für große Dateien
+- `client_max_body_size 50M;` - Erlaubt große Uploads
+
 ## Lizenz
 
 MIT
diff --git a/app/api/daily/route.ts b/app/api/daily/route.ts
index 85affeb..0c62d09 100644
--- a/app/api/daily/route.ts
+++ b/app/api/daily/route.ts
@@ -1,18 +1,12 @@
 import { NextResponse } from 'next/server';
 import { PrismaClient } from '@prisma/client';
+import { getTodayISOString } from '@/lib/dateUtils';
 
 const prisma = new PrismaClient();
 
 export async function GET() {
     try {
-        // Use timezone from environment variable (default: Europe/Berlin)
-        const timezone = process.env.TZ || 'Europe/Berlin';
-        const today = new Date().toLocaleDateString('en-CA', {
-            timeZone: timezone,
-            year: 'numeric',
-            month: '2-digit',
-            day: '2-digit'
-        }); // Format: "2025-11-21"
+        const today = getTodayISOString();
 
         let dailyPuzzle = await prisma.dailyPuzzle.findUnique({
             where: { date: today },
diff --git a/app/page.tsx b/app/page.tsx
index f930c14..75daf04 100644
--- a/app/page.tsx
+++ b/app/page.tsx
@@ -1,4 +1,5 @@
 import Game from '@/components/Game';
+import { getTodayISOString } from '@/lib/dateUtils';
 
 export const dynamic = 'force-dynamic';
 
@@ -14,7 +15,7 @@ if (process.env.NODE_ENV !== 'production') globalForPrisma.prisma = prisma;
 
 async function getDailyPuzzle() {
   try {
-    const today = new Date().toISOString().split('T')[0];
+    const today = getTodayISOString();
     console.log(`[getDailyPuzzle] Checking puzzle for date: ${today}`);
 
     let dailyPuzzle = await prisma.dailyPuzzle.findUnique({
diff --git a/lib/dateUtils.ts b/lib/dateUtils.ts
new file mode 100644
index 0000000..639b417
--- /dev/null
+++ b/lib/dateUtils.ts
@@ -0,0 +1,8 @@
+export function getTodayISOString(timezone = process.env.TZ || 'Europe/Berlin'): string {
+    return new Date().toLocaleDateString('en-CA', {
+        timeZone: timezone,
+        year: 'numeric',
+        month: '2-digit',
+        day: '2-digit'
+    });
+}
diff --git a/lib/gameState.ts b/lib/gameState.ts
index 0489286..90f9690 100644
--- a/lib/gameState.ts
+++ b/lib/gameState.ts
@@ -1,6 +1,7 @@
 'use client';
 
 import { useState, useEffect } from 'react';
+import { getTodayISOString } from './dateUtils';
 
 export interface GameState {
     date: string;
@@ -31,7 +32,7 @@ export function useGameState() {
     useEffect(() => {
         // Load game state
         const stored = localStorage.getItem(STORAGE_KEY);
-        const today = new Date().toISOString().split('T')[0];
+        const today = getTodayISOString();
 
         if (stored) {
             const parsed: GameState = JSON.parse(stored);
diff --git a/next.config.ts b/next.config.ts
index a0043f5..8e3c525 100644
--- a/next.config.ts
+++ b/next.config.ts
@@ -9,6 +9,9 @@ const nextConfig: NextConfig = {
       bodySizeLimit: '50mb',
     },
   },
+  env: {
+    TZ: process.env.TZ || 'Europe/Berlin',
+  },
   async headers() {
     return [
       {