Unable to permanently forget a WiFi network I have an 802.11ac router at home with both 2.4Ghz and 5Ghz connections and separate SSIDs for each. In most parts of my home, the 5Ghz connection is utterly useless, which I learned the hard way from my phone regularly connecting to it and then failing to do anything while it does. So, of course, I told my phone to "forget" the connection.

But since Google backs up all my WiFi networks and syncs them with all my devices, which is a great feature, it constantly restores this WiFi network to my Nexus 6 (and did the same to my 5 before that) without my realizing it until I notice my phone being useless at home again and find that it's reconnected to it. I'll forget it again, it's fine for a while, and then after an unknown period of time it's back.

Anyone know how to PERMANENTLY forget this network from my Google account?
I experienced the same behavior, and through quite a bit of trial and error, I have a pretty solid theory on why this happens.

I think as a "convenience", Android looks for 5GHz networks sharing the same root SSID as a 2.4GHz network and assumes that the password is the same. So for instance, if you have MyNetwork and MyNetwork (5GHz), you can connect to MyNetwork and Android will automatically try the same credentials on MyNetwork (5GHz).

There's nothing I've found on the Android side that will prevent this. The only thing you can do is to change the SSID of the 5GHz network so that it's completely different from the 2.4GHz SSID.