Default HTTP port is 8081 (sirv dev server often uses 8080).
## Frontend
Set `VITE_DEV_WS_HOST=127.0.0.1` in `.env.development` (already set). Then:
```bash
npm run dev
```
Open the app URL (e.g. http://localhost:8080). The app will connect to `ws://127.0.0.1:81` and receive a device list of two mock devices; dashboard and charts will show mock data.