Please help! Triple Play Modem Ethernet Issue

The xfinity supplied wireless modem has 2 ethernet plugs that we have wired to 2 desktops as well as 2 phone jacks. I disconnected 1 of the computer ethernet cables and plugged it into a TPL-406E (two 500 Mbps Range Extender Adapters that uses any electrical outlet to create a range extender via the homes electrical wiring). I then plugged the other adapter into a wall plug downstairs and that into a wireless router to provide WIFI to a TV that has connectivity issues. The problem is that the xfinity modem/router is not supplying a signal to the 1st TPL-406E range extender module which is wired into the router/modem. The normally green light at the ethernet connection plug site at left of each plug on the rear of the modem is off and is blinking orange on the right side of the plug going to the range extender. Ran a new cat 6 cable and the other ethernet plug is working fine to the desktop. (Yes, I swapped connections and cables etc) Thanks in advance for your assistance!