Troubleshooting

Issue	What to check
Stays `SEARCHING`	Send `@HLWD_\r` while the server is probing; confirm 115200 baud and correct cable/port.
Wrong port after replug	Restart Serial API server and client device.
`#UNK` on query	Status not yet populated in the API backing store (e.g. never stopped at a station)
`#ERR` on value	Improper command received; check for typos and framing `_\r`).