SenseCAP S2120 disconnecting everynight

We are having issues with a S2120 unit: disconnects at nights.
We observe no sending from 0-8am everyday.
Batteries have been replaced and coverage is very good, with LOS and -60dBm.
Other devices are using the same infrastructure overnight.
Device has been moved and still happening in both locations.

Seems like a PowerSavings option (happens everynight and day at the same times).

Any clue will be appreciated. Cheers,