diff --git a/app/src/App.tsx b/app/src/App.tsx
index d277c802..ba07b7c1 100644
--- a/app/src/App.tsx
+++ b/app/src/App.tsx
@@ -11,7 +11,11 @@ import { cn } from '@/lib/utils/cn';
 import { usePlatform } from '@/platform/PlatformContext';
 import { router } from '@/router';
 import { useLogStore } from '@/stores/logStore';
-import { useServerStore } from '@/stores/serverStore';
+import {
+  getDefaultServerUrl,
+  isLoopbackVoiceboxServerUrl,
+  useServerStore,
+} from '@/stores/serverStore';
 
 /**
  * Validate that a health response has the expected Voicebox-specific shape.
@@ -105,6 +109,11 @@ function App() {
   // Setup window close handler and auto-start server when running in Tauri (production only)
   useEffect(() => {
     if (!platform.metadata.isTauri) {
+      const serverUrl = getDefaultServerUrl();
+      const currentServerUrl = useServerStore.getState().serverUrl;
+      if (currentServerUrl !== serverUrl && isLoopbackVoiceboxServerUrl(currentServerUrl)) {
+        useServerStore.getState().setServerUrl(serverUrl);
+      }
       setServerReady(true); // Web assumes server is running
       return;
     }
diff --git a/app/src/stores/serverStore.ts b/app/src/stores/serverStore.ts
index c25deba7..d668ebba 100644
--- a/app/src/stores/serverStore.ts
+++ b/app/src/stores/serverStore.ts
@@ -39,10 +39,44 @@ function invalidateAllServerData() {
   queryClient.invalidateQueries();
 }
 
+export function getDefaultServerUrl(): string {
+  const fallback = 'http://127.0.0.1:17493';
+
+  if (!import.meta.env.PROD || typeof window === 'undefined') {
+    return fallback;
+  }
+
+  const { protocol, origin, hostname } = window.location;
+  if (
+    (protocol === 'http:' || protocol === 'https:') &&
+    origin &&
+    hostname !== 'tauri.localhost'
+  ) {
+    return origin;
+  }
+
+  return fallback;
+}
+
+export function isLoopbackVoiceboxServerUrl(url: string): boolean {
+  try {
+    const parsed = new URL(url);
+    return (
+      parsed.port === '17493' &&
+      (parsed.hostname === '127.0.0.1' ||
+        parsed.hostname === 'localhost' ||
+        parsed.hostname === '[::1]' ||
+        parsed.hostname === '::1')
+    );
+  } catch {
+    return false;
+  }
+}
+
 export const useServerStore = create<ServerStore>()(
   persist(
     (set, get) => ({
-      serverUrl: 'http://127.0.0.1:17493',
+      serverUrl: getDefaultServerUrl(),
       setServerUrl: (url) => {
         const prev = get().serverUrl;
         set({ serverUrl: url });
diff --git a/web/src/platform/lifecycle.ts b/web/src/platform/lifecycle.ts
index 14156180..20fa40c8 100644
--- a/web/src/platform/lifecycle.ts
+++ b/web/src/platform/lifecycle.ts
@@ -1,12 +1,12 @@
 import type { PlatformLifecycle, ServerLogEntry } from '@/platform/types';
+import { getDefaultServerUrl } from '@/stores/serverStore';
 
 class WebLifecycle implements PlatformLifecycle {
   onServerReady?: () => void;
 
   async startServer(_remote = false, _modelsDir?: string | null): Promise<string> {
     // Web assumes server is running externally
-    // Return a default URL - this should be configured via env vars
-    const serverUrl = import.meta.env.VITE_SERVER_URL || 'http://localhost:17493';
+    const serverUrl = import.meta.env.VITE_SERVER_URL || getDefaultServerUrl();
     this.onServerReady?.();
     return serverUrl;
   }
@@ -17,7 +17,7 @@ class WebLifecycle implements PlatformLifecycle {
 
   async restartServer(_modelsDir?: string | null): Promise<string> {
     // No-op for web - server is managed externally
-    return import.meta.env.VITE_SERVER_URL || 'http://localhost:17493';
+    return import.meta.env.VITE_SERVER_URL || getDefaultServerUrl();
   }
 
   async setKeepServerRunning(_keep: boolean): Promise<void> {