Apple TV 3rd Generation Box

Installed the Xfinity Stream App on my apple tv box. Go thru authentication and it tries to load the app, and then it exists saying this app currently does not work with this device. What I have done power reset to apple tv box, power reset of XFI gateway no joy. Deleted and restalled xfinity streaming, still get the same results. Using IOS version 17.5 and I have the apple tv box connected via ethernet cable to Xfi gateway. Also I am on my home network. Any ideas?