I’ve been trying to get a solution to my intermittent wireless connectivity problem for a long while now (ie several years), occasionally consulting this forum for possible answers. I’ve reached the conclusion (rightly or wrongly) that this problem is about mobile devices.
We have 2 android phones and an old ipad. For the sake of this conversation, I’ll point out that the ipad and Moto G4 phone both connect to the 5 Ghz channel, whilst volumio and the Nokia 7.1 phone connect to 2.4 Ghz. (The Moto is running Android v7, and the Nokia is v10.)
Now, I often find that I lose connectivity from the Nokia, but if I immediately try again using either one of the other 2 devices, I get a connection. Furthermore, if I then retry on the Nokia, it connects!
There have been exceptions to this scenario, but in general, the Moto and the ipad reliably connect, but the Nokia is very tempermental.
Hopefully, my comments may provide some useful input to this issue.