Xfinity Gateway Capping Ethernet Speeds at 100 Mb/s

My Xfinity Gateway’s ethernet ports are limited to 100 Mb/s. I have confirmed that the issue is related to the Gateway and not my hardware. 

Here are the troubleshooting steps I have already taken. 

• Reset the Gateway in multiple ways (by unplugging the device for 10 minutes, via the Xfinity website reset modem, doing a hard reset via the small reset button on the router/modem, and resetting from the modems administrator troubleshooting panel)
• I have connected to the Gateway as an administrator and confirmed that the hardware settings are correct
• Confirmed that the device I am connecting (Laptop) connects to other networks at gigabit speeds without issue.
• I have updated all LAN/Ethernet/Wifi Drivers on my device, and uninstalled and reinstalled the Ethernet Devices on the PC. 
• Tried two separate Cat 6 cables which both work flawlessly at gigabit speeds when connected to another network.

I have isolated the issue to the Xfinity gateway. All of the hardware I am using works at gigabit speeds when connected to my work network, but caps at 100 Mb/s when connected to my home network. 

I have already spent hours on the phone with people resetting the router and asking me if I have tried a different cable despite providing all of this information immediately at the beginning of the call. Xfinity chat is useless and refuses to connect me to a live agent and puts me in an endless loop of asking the same questions.