CM1000

When I plug the ethernet cord from the CM1000 to the wireless router, internet works fine.  But sometimes we shut off the wifi (wireless router) in the house, so I just want to plug directly into the ethernet port on the CM1000 to my computers ethernet port.  

Frustratingly, none of my computers work when plugged directly into the CM1000 ethernet port.  tried 3 apples and 2 windows computers, none work when plugged in direct to the CM1000.    And I can't access the CM1000 either with the ethernet cord direct.  in fact, nothing works and I no longer have internet when plugged directly into the ethernet.

My suspecion is comcast ifsup to something nefarious in cohots with Netgear and they are disabling my hard connection (via ethernet) so I'm forced to go through my wireless router for any internet connections.  Please, stop with the stupid answers like is my modem turned on and change the ethernet cable.  Did all the low hanging fruit suggestions and nothing works.  

I am on xfinity GB service and have talked to them about the connection, and everything appears to be fine, since my wi-fi network works when I plug that router into the Netgear CM1000.  albeit considreably slower then the 1GB/sec promise; I'm at 350 MB/sec.  

Is comcast or netgear to blame for sabatoging my hard connection to the CM1000?