Wifi channel 11. However, this channel collides with Zigbee channels 23-26
Solution! I hope it helps someone.
I just went through the same stuff with Aqara wireless switches and tried everything people (and LLM) recommended - nothing worked and hours passed on.. The device blinked the pairing mode and I pressed the button every 1-2 seconds for it not to fall asleep - still nothing - no device found for pairing. Debugged everything, changed the settings, ..
Then I opened the Aqara switch up and checked the battery's voltage - it was 2.9 Volts. I changed it with a battery that had 3 Volts and pow, it worked.
PS! ALSO check that the Aqara's battery holder clip is tight - it loosens with changing the battery and you have to really push it back against the battery or else it will most probably not get the power needed to pair because of bad connection and battery depletion. It seems pairing requires more power than normal use.