Connection to Conbee (I) sensors get lost

Hi,
since a while a regulary loose connection to my sensors (temperature, movement,fire alarm). Values are not updating on the dashboard anymore and in phoscon values are not updated either. Interestingly i still can control my lights that are configured with Phoscon. It sometimes helps to restart my server, but not always. I did set up HA from scratch because i thought something in the config was f###ed, but i still lose sensor connection.

Any idea what that could be? Hardware defect of the conbee stick?

Thanks for help!