# Work through a problem

> Start with the smallest known-working path, then add channels, radios and recording load.

## The sensor does not appear

For a Linux sensor, confirm power and first-boot completion. Check its DHCP address and whether the phone can reach that network. Discovery may not cross VLANs even when a manually entered address works.

For C5, use known firmware, a reliable power/data cable and the app’s Bluetooth discovery. Check the requested Bluetooth/Nearby devices permission. A USB-powered board that does not advertise may be held in download mode; use the [C5 recovery instructions](/sensors/esp32-c5/#trouble).

## The device appears but will not connect

For SSH, check username, password, address, routing and SSH availability. Discovery is not authentication. For BLE, verify that the intended board is selected and that another session is not already using it. Reconnect after correcting the condition.

## The AP list is empty

Check the selected device and radio, start state, channels and received counters. Test against one nearby AP on a known supported channel. Allow a sweep time to revisit its channels. On C5, firmware starts idle until the app commands a scan.

If counters advance but the list does not, record the app and firmware versions and the exact scan configuration. That distinguishes a display/update problem from no received traffic.

## Only one of several C5 boards seems active

Confirm every intended board is connected and included in the app’s scan assignment. Identical advertising names can make it easy to select the wrong device. Check activity per board and the installed app/firmware versions before interpreting a multi-board result.

## DFS or 6 GHz is missing

DFS support depends on driver, radio, country and operation. For 6 GHz, confirm you are using a supported Linux adapter; C5 does not support it. The [scanning guide](/features/scanning/#tips) explains country configuration and the self-managed Intel difference.

## USB flashing fails

Try a known data-capable cable and a direct USB port. After a failed attempt, unplug and reconnect the C5. For ROM download mode, follow the board’s BOOT/RESET sequence and release BOOT after flashing. The manual flashing instructions explain the documented `--no-stub` route.

[Full C5 recovery guide →](/sensors/esp32-c5/#trouble)

## Captures pause or stop early

Check sensor and phone power, link stability, available storage and the recording destination. Inspect the file duration and timestamps. A continuing UI timer or temperature log does not prove continuous packet delivery.

The [thermal report](/field-notes/nanopi-thermal-testing/) documents packet gaps and firmware restarts separately. A low reported BE200 temperature does not rule out other hardware, firmware or transport problems.

## Ask for help with enough context

Include the app build, phone/OS, sensor image or firmware, board and adapter, connection method, country, channels, and the shortest reproduction. State whether the issue is discovery, connection, received counters, displayed results, or recorded packets.

[Support and contact →](/support/)