xb8 multi-gig port 4 only gives 300mps where ports 1-3 with same cables/connections deliver close to 1000mbps

X2 multi-gig level service, a slightly beat up xb8 brought today by xfinity

using cat8 patch cable directly from port 4 of the xb8 to a laptop with a 2.5G nic adapter, only achieve 300mbps

-xb8 admin tool indicates the lan port is achieving a 2500mbps connection, but observed speed never exceeds 375mbps

using same patch cable directly from port 1,2,3 of the xb8 to same laptop observed speed > 900mbps

- same observed speed issue whether bridge mode engaged or disengaged

using cat8 patch cable direct from port 4 to the multi-gig port WAN on a netgear RAXE500 router, and then connecting patch cable from a multi-gig LAN port on the router to the laptop with the 2.5G nic, still only 300mpbs. This is despite the xb8 LAN status showing a 2500mbps connection established on port 4, and the router wan status showing a 2500mbps connection established with the xb8

using same connection config except connecting from the 1.0g ports 1,2,3 on the XB8 results in > 900 mbps observed speed

I can conceive a few scenarios, but does anyone have other ideas?

1) My xb8 is somehow mechanically faulty on port 4?

2) Xfinity is somehow not provisioning my specific xb8 to allow multi-gig use on port 4, despite my subscribing to its "X2" multi-gig service tier?

3) Xfinity has not provisioned the physical network in my local geography to allow port 4 to work on customers with xb8s or xb7s?

Since 900mbps speed is available using this XB8's 1.0G ports directly to a laptop in gateway mode and through a 3-rd party router in bridge mode, its not the cables, its not the router

The fact that port 4 can only deliver 300mbps through the same cables to the same devices and routers suggests...what?

Thanks in advance

Responses

CCMichelle

Problem Solver

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788 Messages

2 years ago

@cbonn, thanks for taking the time to reach out to us regarding your slow speeds. Is port 4 the only port that you are having an issue with? What other devices are you connecting to other ports?

cbonn

New Poster

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5 Messages

@XfinityMichelle Thank you for your reply and follow-up.

There are no other devices connected via network cables to any of the other ports on the xb8. Just a single cat8 patch cord between the xb8 gateway and a single (laptop) with a 2.5gb nic. And no other devices are connected to the xb8's broadcast wifi at the time, so truly a "single-device-connected" test.

When only a single device is connected with a single cat8 patch cord to port 4 (the multi-gig port) on my xb8, I achieve < 400mps observed speed. Same device connected same way same cable to ports 1,2, or 3 achieve > 900mps observed speed. Same observed speed differential if I put an unmanaged switch between the XB8 and the device. When looking at the negotiated connection between the xb8 and the device (laptop with 2.5gb nic), the xb8's diagnostic interface (under the LAN submenu) indicates a 2500mbps negotiated connection when plugged into port 4, but slower < 400 mbps observed speed. Indicates the expected 1000mbps negotiated connection when plugged into ports 1,2,3 and then > 900 mbps observed speed.

Either:

1) my xb8 isn't properly configured or provisioned for multi-gig usage, or

2) my local geography isn't provisioned for multi-gig service, or both

In particular, because port 4 delivers less than half the observed speed as ports 1,2,3, I'm optimistic that the xb8 itself is "bad" or improperly provisioned.

Need to swap it for a fresh xb8 at either a retail location or have a tech bring another one to test that, obviously.

Can you assist?

2 years ago

XfinityEva

Official Employee

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1.7K Messages

@cbonn

Thank you so much for getting back to us and your feedback on the possible causes of the port issue. We can definitely help in trying a few troubleshooting steps on our end like sending different signals to the modem. This will also help us record the troubleshooting on there.

We can circle back here in the public post to the steps taken and if needed have you stop by your nearest Xfinity Store to switch the XB8 or have us set you up with a follow-up visit with a tech.

Please send us a direct message with your name and service address to get started.

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2 years ago

Shankarhokie

Contributor

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58 Messages

2 years ago

Is your laptop a Dell?

cbonn

New Poster

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5 Messages

@Shankarhokie Yes (alienware). What could the issue be with brand? Laptop has a 2.5gb NIC.

2 years ago

Your Home Network

cbonn

xb8 multi-gig port 4 only gives 300mps where ports 1-3 with same cables/connections deliver close to 1000mbps

CCMichelle

cbonn

XfinityEva

Shankarhokie

cbonn

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