@cretepete
You'll probably have to do a factory reset on your Google Home Mini if you did not "forget" your old Wi-Fi network on your Google Home Mini while it was still on your old network:
"Change the Wi-Fi network of your speaker or display
If your speaker or display is already set up on a Wi-Fi network but you need to change your Wi-Fi password or connect it to a new network, you'll need to forget your current Wi-Fi network and set up the device in the Google Home app again.
Open the Google Home app.
Tap and hold your device's tile.
Tap Settings Settings and then Device information.
Tap Wi-Fi and then Forget this network.
Return to the Google Home app home screen and follow the setup steps above to connect your device to a new Wi-Fi network.
If you get an error message that says 'could not communicate with your [device]' when you try to forget your network, or the steps above don't work, you'll need to factory reset your device and set it up again."
https://support.google.com/googlenest/answer/7170507?hl=en-AU&sjid=10769823139982880016-NA
