Update of 18th of April 2021:
Starting point : OCS version 2.31.
- Unstable (no more than 1 minute Up Time) if I activate the power relays.
- Even if I do not activate the power relays, the system hangs and reboots, but it takes more time (Up Time reset during my lunch time, then reset in less than 10 minutes now that I am attending).I tried to put WATCHDOG OFF as you suggested and it is worse : The OCS web page freezes and can no longer be opened. I returned to WATCHDOG ON_CC. I suppose that Up Time counter lets me know the time since the last hang-up and reboot.
I have copied exactly the arduino codes for the weather sensors that you have profided in the file named "Functions" under "Weather.ino examples".
Is there a way of debugging all this ?
Next thing I will do is connect an original TSL2591 sensor from Adafruit and try to get correct SQM data but I am getting short of ideas to solve this issue of instability.
Any help would be appreciated.