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WillLombard
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Monday, February 14th, 2022 9:35 PM

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Modem not Transmitting Gigabit Speed

I am currently getting Xfinity Gigabit Internet using a SURFboard SB8200 and 3 Mesh Google Wifi routers (one connected to the modem, the other two on each floor on top of each other.) I had an Xfinity tech come out today to check my service since I've been getting 300 Mbps (worse on the second and third floor. The tech confirmed that my router is receiving gigabit speeds, but isn't sending it out to my routers. I tried looking to see if I needed to upgrade any firmware, but I could not find that or anything of support on Arris' website. Does anyone have any troubleshooting ideas as to why my modem is not transmitting the speed it is receiving?

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3 years ago

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EG

Expert

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110K Messages

3 years ago

For a test, what speed does a computer that is hardwired directly to the 8200 cable modem (no router in the mix) with an ethernet cable get ?

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WillLombard

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@EG​ Similar speeds as wifi when hardwired into the modem

3 years ago

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BruceW

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26.3K Messages

3 years ago

I am currently getting Xfinity Gigabit Internet using a SURFboard SB8200 ...

Note that the SB8200 is not rated for use with Gigabit service. https://www.xfinity.com/support/devices says the device is approved for use with plan speeds up to 957 Mbps. Using devices on Internet speed tiers for which Comcast has not approved them tends to produce unexpected results, often speeds well below the manufacturer's ratings. You should upgrade the device, or choose a lower plan speed for which the device is approved.

Ever since Comcast changed the speed for Gigabit from 1000 to 1200 Mbps they require compatible devices to have an Ethernet port capable of line speeds of at least 2500 Mbps. The SB8200 does not have one.

(edited)

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WillLombard

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3 Messages

@BruceW​ Even if its not compatible with gigabit, the speeds I am getting are not up to what I am paying for/max the modem can handle

3 years ago

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EG

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110K Messages

@WillLombard​ 

What happens is that since it is not compatible with their gig speed tier, it will default to using an even slower configuration file so will get even slower speeds than before.

I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Please mark an Accepted Answer!tick
I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Please mark an Accepted Answer!tick
I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Please mark an Accepted Answer!tick

3 years ago

EG

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110K Messages

3 years ago

That was next.

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