Ethernet Stopped Working

While WIFI remains fully functional, all of my wired devices have lost internet access.  The wired devices include 3 Windows PC's and 1 Vonage VOIP unit.  All three PC's show connected to the network but without internet access.   The lights on the back of the gateway are green and sometimes orange.   While 2 of the PC's and the VOIP are connected through switches, one PC is directly connected.

I have been using the wired connections for a couple of years (successfully) and there have been no physical changes to the set-up that precipitated the loss of internet connectivity.   

I have tried powering down and restarting the gateway and all connected devices.  I have also tried resetting using the reset switch on the back of the gateway.  

Starting to sound like something is wrong with the gateway, since all wired connections appear to be affected.  Thoughts?