Wifi perma reboots in loop at a certain time

hi all

everyone knows this kind of friend.. i share an openwrt router with a room mate and he has more knowledge about openwrt than me. he liked to play pranks sometimes. now he is playing another prank and at a certain day time (usually around 10pm) the wifi perma every XX minutes restarts for hours. i can tell that the LAN connection still works. its just the wifi that goes crazy since a few days now. i know its him.
unfortunately i have no idea where to look for this prank code. the "sheduled tasks" is empty and all other settings do not show any sign of manipulation. so i thought: okay time to use WinSCP and look into deeper settings via SSH. but here is the problem: i have no idea what i have to look for or where i should look for (ssh connection view winscp was established successfully btw). for starters, i set the conloglevel, cronloglevel and klogconloglevel to 0 (zero) to have the most detailed log list. but somehow the prank did not appear yet. i also think he noticed i set the log levels to 0, so he maybe already removed the cause for the restarts loop for now. (at least i think it is a wifi restart loop. why? because wifi is not completely turned off, but always comes back for 1min every 1-2min, just to disconnect me again). anyone has any idea what command could cause this and where i sohuld look for it? i think its not IP related, because none of my devices can find the wifi anymore when it this prank starts. so i guess its a global wifi command.

find /overlay/upper/etc -type f ! -name ca-certificates.crt \
    -exec head -n -0 {} + | grep -v -e ^# -e ^$