Xfinity App is Showing Old Modem

I received a new Xfinity Gateway/Modem.  However, the app is showing that I am offline and have no connectivity, but I have internet and everything is working fine.  I believe the app is still associated with the old modem.  This is preventing me from connecting pods through the app to the new gateway/modem - amongst - other issues.  I have deleted the app, reinstalled the app, done it all.  With no success.  Please help!