That can be infuriating, especially since you used the same SSID and password expecting everything to magically reassociate. The Nest cameras occasionally "remember" the internal ID of the old network rather than the name and password, so even though the data looks the same, the router is technically a new network to them. Attempt to open the Google Home app, tap on every camera, and see if you can possibly connect to Wi-Fi again without a full factory reset — some models will have a feature to update the connection from within the app's settings. If not, pull the camera out for a few minutes, put it back in, and wait to see if it will recognize the network again. If it continues to fail, the only guaranteed solution is to de-add the camera from the Home app and reinstall it as a new device. It's frustrating, but once they're added back, they'll connect normally with the new router settings.
