Zigbee2Mqtt : losing signal

Hello I am using HA with USB CC2531 dongle with some Aqara moving sensors (old an new), buttons , switches and everything is working great but, sometimes, the link quality goes to zero!
(Have a look at the attached file).

Also, between the CC2531 and on the sensors marked in red there is an Aqara switch always on.
Is this normal ? How can I debug it ?