Xiaomi Mi Router 4A Gigabit Edition (R4AG/R4A Gigabit) -- fully supported and flashable with OpenWRTInvasion

Anyone have any idea why I lose connectivity to lan devices that are connected via wifi?
It happens after about 12 hours and only rebooting the rooter fixes the issue for me.

I've seen it mentioned in several threads with no real solutions. changing GTK delay didn't help.