Nuki 3.0 Pro looses connection despite AP is next to it

I have a 3.0 Pro and a couple of weeks ago I switched my router to a UniFi Express.

I’m now constantly having connection issues. Seems like a particular issue with UniFi routers from what I can read here. Also when I switch back to my old Eero 6pro seems to work OK all the time.

I created a new SSID where the Nuki connects (it’s only for the Nuki) following this configuration but that doesn’t seem to have helped.

I’m very frustrated as I usually lock my door when I’m already outside the apartment. Who can I contact? What can I do?

Is there a solution for this? I see this thread and I see no solutions. This might be enough reason to activate a warranty request since I got my Nuki just a few months ago.