Gateway/router not discovering ethernet connected devices behind LAN bridge

I have just installed an Xfinity WiFi Gateway/Router and set up my home network.  All my wireless and directly connected ethernet devices and those behind the first bridge were discovered and work well, but I have a second ethernet bridge in another room with several addional devices that aren't discoverable and don't see a live internet connection.   I've tried power cycling everything and rebooting the Gateway.  Nothing seems to work.   Don't think this is a physical connectivity issue since this all worked well with my Cisco WiFi Gateway/Router that I replaced.  The only thing I swapped out was the Gateway.

Has anyone seen and/or resolved this kind of issue?  Guess I could just put the Xfinity box in bridge mode, but don't want to give up just yet.