XB7 2.5G port only negotiating at 100Mb

Hi I'm having trouble with my XB7 gateway. The 2.5 Gb port (with the red mark) is only negotiating at 100Mb (amber light) to my Ubiquiti UDM-Pro. I've tried multiple multi-gig devices (iMac Pro, a CalDigit 10G adapter) and cat6 Ethernet cables. I previously had a Motorola gateway that negotiated 2.5Gb with the same gear. The 1 Gb ports negotiate fine. Speed to the gateway in the Xfinity app is fine - 1200Mbps. It seems like just a problem with this port. I see other users have had this same issue. Do I need to swap out my gateway?