Troubleshooting offline sensors

A device shows as offline when the platform has not heard from it for longer than expected. FreshControls raises an offline alarm for that device rather than letting it disappear quietly, and escalates it like any other alarm — so silence is something you get told about, not something you have to notice. Some devices retain a bounded backlog of readings while disconnected, but storage capacity and recovery depend on the device and firmware. Treat an offline device as a coverage gap to close quickly; stored readings cannot trigger a live temperature alarm while they are offline. Work through these checks in order.

1. Confirm it is really offline

Open the device and check the last seen time. A single missed report during a long reporting interval is normal. Treat a device as offline only once it has clearly missed several expected check-ins.

2. Check power

• Battery sensors — replace the field-replaceable batteries and confirm the sensor powers up. A depleted battery can stop reporting.
• Wired boards and gateways — confirm the power supply or PoE injector is live and the status light is on.

3. Check range and placement

• Wi-Fi sensors — a freezer's metal walls attenuate the signal. Confirm the sensor is within reach of an access point and that the network password has not changed.
• LoRa sensors — confirm a gateway is powered and within range. Thick walls, racking, and distance all cut range; moving a gateway closer often fixes a stubborn sensor.

4. Check the gateway

If several sensors went offline at once, suspect the gateway they share rather than the sensors themselves.

• Confirm the gateway is powered and its uplink light is healthy.
• Current gateway firmware uses Wi-Fi uplink. Check access-point coverage, the network password and internet connectivity at the gateway.
• Ethernet and cellular backhaul are planned. Confirm the supported connection for your gateway instead of relying on an unused cable or SIM.

5. Confirm it is back

Once a device is back on the network its next scheduled report clears the offline alarm and the history resumes. Review the graph and incident history after reconnection. Any recovered backlog must keep its original measurement timestamps and must not imply that live alarm delivery occurred during the outage. Missing readings stay visible as gaps; a compliance log should show what was actually measured, never a reconstruction.

Still offline?

If a device stays dark after power, range, and gateway checks, contact support with the device serial and we will help you narrow it down.

Related

• Getting started
• Alarm profiles basics