iPhones defaulting to Xfinity Wi-Fi instead of home Internet

For about two weeks, my family’s iPhones are defaulting to the Xfinity Wi-Fi Internet, instead of our home Internet. When when we use our iPhone settings to select our home Wi-Fi, we get a window that says cannot connect to the Home Internet.

Have restarted the gateway, have turned on and off the cell phones, have checked for cell phone updates, but none of those options have solved the defaulting to Xfinity Wi-Fi.

when I attempt to use the troubleshooting chat bot, I can’t be specific about the issue because I am only provided choices instead of the ability to type the problem.

Is anybody have any advice?