@joncot1812
For some older Google Nest cameras and doorbells, you could go to Settings | Home info | Home Wi-Fi Help and update the Wi-Fi settings of your offline cameras if you were within Bluetooth range of the cameras and had Bluetooth turned on on your phone: https://support.google.com/googlenest/answer/9223711?hl=en#zippy=%2Cuse-the-nest-app
If this doesn't work, then Google Nest's first recommendation is to set the network name (SSID) and password of your new router to the same values used on your old router: https://support.google.com/googlenest/answer/9223711?hl=en#zippy=%2Ctry-the-same-network-name-and-pa...
If that isn't possible, then Google Nest's recommendation is to remove/delete your cameras from the Google Nest app while still on the old Wi-Fi, then do a factory reset, and then re-install. If you did not remove the cameras from the Google Nest app while still on the old Wi-Fi, you may need to contact Support (https://support.google.com/googlenest/gethelp) if you run into errors.
