First, confirm that you can get the controller into ‘awaiting Wi-Fi’ state (2nd quadrant blinking).
Then, turn off mobile data on the phone. Open your Wi-Fi settings and you should see a Rachio-xxxxxx network, where xxxxxx is the last 6 characters of the MAC address. Connect to that network (of course you won’t have internet access) and let the phone sit for two minutes. If a message pops up warning you of no connectivity, choose the option to remain connected. Now, reconnect to your Google Wi-Fi, run the app and try to connect the controller.
If you fail (still quadrant 2 blinking), try to use a different device (Windows, Mac or Linux) to provision the controller. See
OTOH, if you fail but you get a different error (report details), then your Wi-Fi or network configuration may be blocking the controller from connecting to the cloud. To confirm this, temporarily set up a phone as a mobile hotspot (confirm with a second phone that it’s working properly) and try to connect the controller to that. If it succeeds, we can then see what’s different about the Google connection.
If you don’t have two phones for the hotspot test, use your working phone as the hotspot and use an old phone or tablet (no SIM card needed) to run the Rachio app. If you don’t have an old phone, use your phone as the hotspot and a desktop or laptop (as described above) to provision the controller.
ISP? Modem make/model? If modem is a gateway (has more than one Ethernet port), do you have it in bridge mode? How many Google Wi-Fi devices do you have? How are they connected to your modem? Are they in bridge mode?