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Monday, April 14th, 2025 2:08 AM

Not getting upload speeds I paid for.

I have an Arris S33 and subscribed to the 2100Mbps plan. I am getting the 2100Mbps download, but am only receiving 40 Mbps upload.  I am being capped at 40Mbps and not getting the 306 Mbps upload in my plan.  I read that there needs to be some provisioning done in the configuration. 

Gold Problem Solver

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26.3K Messages

2 days ago

... Arris S33 ... not getting the 306 Mbps upload in my plan ...

Realize that although Comcast calls some devices "Compatible" and some "Recommended", for all but a few devices those designations only mean "compatible/recommended for use with their Internet service", and not necessarily approved for the higher upload speeds introduced in 2023.

The S33 is not compatible with those speeds. Only a few retail devices are. See the "Next Gen" list at the top of the "All Compatible Devices" PDF linked near the bottom of https://www.xfinity.com/support/devices (at the moment that link points to https://assets.xfinity.com/assets/dotcom/projects/cix-4997_compatible-devices/2025.03.25 Full List of Compatible Devices.pdf, but this changes from time to time).

For faster upload you need one of Comcast's newer rental gateways (XB6, XB7, XB8) or one of the few retail devices shown in the "Next Gen Speed Tier" group at the top of the "All Compatible Devices" PDF:

  • Hitron Technologies CODA or CODA56
  • Netgear CM2500, CM3000, or CBR750
  • ARRIS/Surfboard G20, G34, G36, G54, or S34
  • Ubiquiti UCI 

Comcast/Xfinity could make all of this much simpler and clearer, but they have chosen not to do so.

For additional requirements for faster upload see https://forums.xfinity.com/conversations/customer-service/upload-speeds/677b01a7121aae71d76926bf?commentId=677b05b23423b47b4071a8d0&replyId=677bd66e7699a97c89069e62

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Official Employee

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2.1K Messages

8 hours ago

 

user_m6m5t8 @BruceW is on point with this one. The S33 would not be an approved modem for the higher upload speed. If you check out the list in the link Bruce provided, you can see the s34 is approved for the Next Gen Speed Tier. I you are still having the same use when using one of the devices approved for Next Gen Speed Tier, we would be happy to help take a closer look for you. 

 

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