Google Nest Community

I have set up a new WiFi using Google WiFi Pro. I'm trying to connect my existing Nest Protects to this. I have reset the devices but when trying to scan the QRs the app tells me the device is still on my account and I should delete it first. However...

My doorbell has worked fine with my old network, but I have just set up/installed Google WiFi Pro and the doorbell won't connect. At the moment it's sat about 2" from the router and led is happily pulsing white having been reset a zillion times. Ever...