1 Message

Thu, Mar 18, 2021 2:13 AM

XB7 Modem 2.5GB red port not working as it should

Recently got pushed up to 1200 speed. Obtained XB7 mode, connected several 2.5 adapters to the red 2.5 port using good GAT6 cables. Get links on the cables at 2.5 but speed various speed test only at 100 on the adapters that do work, some adapters don't even link up properly. When I plug a 1gb adapter into this port at a 1gb link I get 1bg download. But with 2.5gb lan link it either doesn't work at all or works at a super low speed of only 100. Anyone else have this problem? Is there a specific adapter that works with this port? Or is there a hidden setting that Comcast needs to enable? I did go over all settings on the NIC, Comcast modem and did check the NIC drivers. I am getting a 2.5 link on the drop, so it's not a cable issue. Other devices work full speed at 2.5 on same wires. 


Official Employee


2.7K Messages

3 m ago

Hello, @user_107b69! Welcome to the Xfinity Forums. 


I'm sorry to hear you are having trouble with setting up your network and we would love to help. We do not have any settings that allow you to get faster speeds through an ethernet port, you will automatically get the speeds you are subscribed to. When you mention using an adapter, can you explain what kind of adapters you are using or what your ultimate goal is here for context? 

I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: CARE, Product, Leadership. We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Solution.tick



2 Messages

I have this same issue.  My XB7 is currently configured as a bridge.  The XB7 is connected to an Aruba 6300M 1/2.5/5G Ethernet Switch which is in turn connected to and Aruba Gateway running Firewall services.  The data path is as follows:

Xfinity Internet <-> XB7 Cable/WAN Interface <-> XB7 Port-4 <-> Aruba 2930M 1/2.5/5G DMZ switch <-> Aruba Gateway/Firewall <-> Aruba 2930M 1/2.5/5G inside switch.

All devices support 802.3bz 1/2.5/5G Ethernet.

When the XB7 is connected to my DMZ 2930M via Port-4 (2.5G port) internet downloads drop to about 400Mbps.  When the XB7 is connected to my 2930M via any of the three 1G ports internet throughput is fine at right around 980 Mbps.

The 2.5G Ethernet ports on the XB7 to not appear to behave correctly when connected to Ethernet devices that support industry standard 802.3bz such as the Aruba 6300M.  This needs to be fixed ASAP in order for Comcast customers on the 1.2G internet plan to have full access to their available bandwidth.


This reply has been converted into a post

Valued Contributor


432 Messages

My Xb7 delivers more then advertised with the 2.5 gig port

This reply has been converted into a comment

New to the Community?

Start Here