Xfinity app is showing my cell phone is connected to internet but it doesn’t connect

My modem is up and running. All diagnostic tests show that things are running normal. The app even shows that mine and my wife’s cell phones are connected. However, neither of our cell phones will actually connect to the internet. Every time we try it gives us an error message that says “unable to join the network”.

I have restarted the modem, forgot the network, reconnected things multiple times and just keep getting the same issue.