Unknown error

My nighthawk router lost its mind during a power outage and forgot its main name. So I had to rename it. All my other wifi appliances from cameras, six conditioners, tv apps, printers, etc were a breeze except for my Rachio3 controller. The Racio3 finds the correct new wifi name, but will not make it to the password screen to log in. That is when I get the unknown error. I have done everything to the controller from praying, disconnect for an hour and redoing step by step, and I get the same error. It’s not a bandwidth or strength issue, as the Racio3 wants to attach to the new wifi name. The app shows the old wifi name, but I conclude that’s not the issue as the Racio3 has not completed accepting the new wifi name. Any ideas?