s33 1gb port not working

I just purchased the s33v2 modem. My old SB8200 worked just fine with both ports, but I wanted to upgrade because I wanted to get full use out of my internet speeds. I have xfinity gigabite internet. I do have a 2nd IP for my account, one hardwired to my tower, one hardwired to the wifi. The 1gb port isn’t sending signal to the wifi router. I called comcast thinking it might be something on their end, new modem and all, but they did everything on their end and believe its a hardware issue, not their end. Any advice would be appreciated.