I am having the same problem. I have Google Fiber, have had it for months. I just got a new iPhone and now the Home App does not recognize my google wifi network. I can not connect to the router to manage the wifi network. When I try to connect the app I go to "What are you setting up?" >> select wifi >> select Google wifi >> it goes through the "looking for devices" routine and then opens back up to "What are you setting up?"
Sorry for the late response, but I wanted to drop in here to help.
I understand that these issues can be confusing but I definitely wanted to stop by and see how I could help.
Just wanted to double check to see if you were still needing help on this? If so, what troubleshooting steps have you tried?
I look forward to hearing from you.