If you do log "info" , then you would see messages like "Wifi client rejected based on ..." in that case it would be access list issue,
but you do not have that I would assume.
I get always one (and only one) error, which is at boot, "DEFCONF, can't find WLAN interface".
Probably it boots too fast before Wifi is up
But it does not create any issue afterwards.
If I change a Wifi parameter, the Wifi interface will indeed switch of for a couple of seconds and come back afterwards.
But never with an error message. And my laptop will reconnect immediately.
Have you updated the router board firmware itself to latest version (not only routeros).
Maybe do netinstall on it as well.
PS: I also apply similar settings on all Wifi virtual i/f. Specially the max client count reduction from 1000 clients
will mean less memory assigned/reserved for buffers, and might improve stability (but this might just be wishful thinking I guess on my side).