diff --git a/backend/src/gps/traccar-client.service.ts b/backend/src/gps/traccar-client.service.ts
index b864162..68515db 100644
--- a/backend/src/gps/traccar-client.service.ts
+++ b/backend/src/gps/traccar-client.service.ts
@@ -300,18 +300,19 @@ export class TraccarClientService implements OnModuleInit {
 
   /**
    * Get the device port URL for mobile app configuration
+   * Returns hostname:port for Traccar Client app to connect to
    */
   getDeviceServerUrl(): string {
-    // In production, this should be the public URL
     const port = this.configService.get<string>('TRACCAR_DEVICE_PORT') || '5055';
-    const frontendUrl = this.configService.get<string>('FRONTEND_URL') || 'http://localhost:5173';
 
-    // Extract hostname from frontend URL
+    // Use the Traccar public URL to derive the device server hostname
+    const traccarUrl = this.getTraccarUrl();
     try {
-      const url = new URL(frontendUrl);
-      return `${url.protocol}//${url.hostname}:${port}`;
+      const url = new URL(traccarUrl);
+      // Return just hostname:port (no protocol - the app handles that)
+      return `${url.hostname}:${port}`;
     } catch {
-      return `http://localhost:${port}`;
+      return `localhost:${port}`;
     }
   }