If one of your sensors are offline:
- Verify that the gateway is online and other sensors at the same location is working.
- Check the RSSI of the last sample. If the signal was weak try moving the sensor or gateway to improve the reception or add another gateway to improve the coverage. See the mounting guidlines: Mounting guideline sensors, Mounting guideline gateway.
An RSSI below -90 dB is weak and below -100 dB is critical low.
- Verify that the sensor is blinking every 3 seconds. If it's not blinking the battery might be dead and the sensor must be replaced.