Xfinity tv issues without xfinity internet services.

I recently upgraded my internet service to Google fiber and dropped xfinity internet, but kept xfinity tv service. Now the apps in the Comcast box will not work, and the stream app on my Roku will not work anymore. Is there a way to let my fiber internet power my Comcast boxes? Plugging internet into the Ethernet ports does not fix the problem. I just want to enjoy the tv service I am paying for, without having to subscribe to their internet service. Please help. Any other ideas?