I totally agree.
While browsing this forum I figured I could try the modified firmware with updated 5.1.0 wifi drivers found here: GL.iNet download site (gl-inet.com).
This partially fixed the issue, with the 2.4ghz looking pretty stable. At least wifi is useable in 2.4ghz. However the 5ghz is still randomly dropping every 2-5 minutes, and I unlocked the region and tried all possible bandwidths, channels, etc. Using a totally free channel doesn’t help whatsoever.
It seems that selecting the “Low” Tx power makes it somewhat more stable than the others, but 5ghz will still drop at some point and after a few times it will give up (won’t accept new connections until a reboot), while 2.4ghz will still be up and running.
So my advice is to upgrade to the above mentioned firmware and stick to 2.4ghz until they release a stable firmware with good wifi drivers.