WIFI draining battery faster than cellular - LG G6

[Android Central Question]

My LG G6 started draining battery on wifi faster than on cellular ( which is weird).

It drains 30-40% of battery at night (around 8 hours) when on wifi, and the signal is perfect, cellular signal also good.

Even If I turn on flight mode and only leave wifi on it drains a lot.

Doesn't matter if it's 2.4G or 5G wifi.
No app seems to be draining that power.
Other cellphones on the same wifi don't drain that much battery (a samsung S7 survives a week on wifi only mode).
Tried entering "SAFE MODE" for the night, nothing changed (means it's some 3rd party app).

Any ideas ?

 

[B. Diddy]

Welcome to Android Central! Actually, if it still happens in Safe Mode, that means it has something to do with the system or some preinstalled app. The next time this happens, go to the Settings>Data Usage​ menu and see if something is using a lot of data during the time of the battery drain.