I learned something that I want to share with as many people as possible. If you have a Nest Audio device and try to connect it to a Nest WiFi and you want to use the Guest Network, IT WILL NOT WORK. You MUST connect it to the primary network. I threw out a perfectly good unit because this nugget of information was nowhere to be found on my searches.
I discovered this because I setup a guest network on my home, mesh, Nest WiFi system and have been slowly moving all my home automation stuff to that network. A couple days ago I disconnected and reset my Nest Audio device and tried to reconnect to my Guest network. Long story short, it did not work and I thought I bricked my Nest Audio. I bought a new one, and to my dismay it had the same problem. Finally I tried going back to the original network and everything worked like a charm.
It never occurred to me that the device would not work on the guest network since I have about 20 IoT devices on it including a Lenovo Brand Smart Clock with google assistant (identical to a Nest Audio in functionality with a clock display)
If Nest is listening some technical info I discovered. While the Home App kept reporting a connection issue after saying connected both my iPad/iPhone running Home App were connected to the network, AND so was the Nest Audio. I saw it on the list of devices connected to the router. Also devices on the guest network can see each other but apparently just not a Nest Audio
