Hi Smanar,
No specific errors in Domoticz log:
2021-12-06 02:22:32.444 Error: YouLess hardware (17) thread seems to have ended unexpectedly
2021-12-06 22:10:04.145 Error: ConBee2: (ConBee2) Device not ready : 2
2021-12-07 04:43:06.218 Error: EventSystem: Warning!, lua script /home/pi/domoticz/dzVents/runtime/dzVents.lua has been running for more than 10 seconds
2021-12-07 22:10:04.108 Error: ConBee2: (ConBee2) Device not ready : 2
2021-12-08 22:10:04.174 Error: ConBee2: (ConBee2) Device not ready : 2
2021-12-09 22:10:04.109 Error: ConBee2: (ConBee2) Device not ready : 2
2021-12-10 22:10:04.138 Error: ConBee2: (ConBee2) Device not ready : 2
2021-12-11 22:10:04.150 Error: ConBee2: (ConBee2) Device not ready : 2
The devices are 230V devices of the type TS130F (Vendor: _TZ3000_vd43bbfq). I have ten of these in use. Two or three of them are always working. The other ones intermittently fail 
Note: the Error: Conbee2: (Conbee2) Device not ready:2 is probably caused by starting a back-up to external SSD on my Pi at that time.