5031NV Residential Gateway Ethernet port

I had a technician come out to help with some internment disconnection problems on my line and he left behind a replacement modem model 5031NV.

My problem is that anything directly connected to the #1 Ethernet port on the back of the residential gateway fails to connect to the Internet.

I've tried all the typical troubleshooting steps like power cycling the modem and trying multiple computers/devices and cables. All the other ports are working fine as is the wireless. I've tried googling around for solutions but the terms Ethernet and port return to many results about problems forwarding ports and I'm running out of ideas.

Is there anything else I can try or am I stuck trying to get ATT to fork over yet another new modem?