Is it possible to try another, different, hardware platform?
I’ve just upgraded & ‘rebuilt’ my OpenWrt config (router + a separate AP). Testing along the way.
I have two router boxes, acquired off eBay that I chose for Gb WAN performance so have a fall back if there’s a snag in a given release (a Linksys WRT3200ACM & a Netgear R7800).
Allows me to put need for debug on the back burner.