Hi all,
TLDR: if you are recently started having issues on wifi connectivity and you are using unifi ap, you might consider to turn off nightly optimizations. This might try to optimize your channels, frequencies in a smart way, maybe too smart.
I have a 3 story house and multiple access points scattered around the floors to have a nice wifi coverage for my stuff. All my access points are unifi branded and i am using unifi network add-on to manage them. I had setup my channels for each AP manually and it has been working great.
In last couple of weeks, i noticed some weird disconnection issues on my home assistant instance but it was also happening to some other devices here and there. I just placed tuya based socket to restart my raspberry pi via internet, if something fails while i am not at home. Home assistant was specifically moving into network down state at late hours (between 11PM to 3AM) in recent days. (3AM signal :-))
Yesterday night, at 3 AM, again, home assistant, couple of alexa devices (mainly all 5ghz clients) were disconnected from network. I spent this morning to fix the access points and apparently this nightly optimizations were the culprit. I just disabled it and will keep you updated.
I will also give another look at my network with these guidelines: https://adrianmace.com/blog/optimising-unifi-performance/