Excellent wif, shows connected, but can't sign in

I'm able to connect to the wifi, and checking the wifi settings everything looks good. I've checked the settings, and it shows that I have the best connectivity. I've reset the apple TV to factory settings, and have the latest updates. When I first bought the unit everything worked fine. Then when I tried to access an app after not having used the unit for many months I experienced this problem. When I plug in an ethernet lead everything works fine. However, my modem is in another room so that is not a practical solution. I've tried various gadgets that lets you hook in to the electrical outlet, but they have been unsatisfactory. The model I have is A1842 (64 GB) which I believe is the Apple TV 4K. Any idea what the issue might be and how to fix it?