So I have a nest wifi setup with 1 router and 2 points. This is a well established network and we have not had any issues for some time, but my mother has recently tried to connect to the network and it seems to connect fine, but her phone is showing no network connection. If you go to YouTube it says no connection at the bottom and the network seems to be down. But every other device on the network work just fine. The phone says connected to the WiFi but the wifi point says the device is offline.
Does she have MAC randomization enabled? Try to disable that.
Does she have Apple iCloud Private Relay enabled? Try to disable that too.