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Visitor

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2 Messages

Sunday, May 25th, 2025 1:14 PM

Aris S33 Modem - Upgraded to 2000/300 mbps Plan

I just recently upgraded to the 2000/300 mbps plan. I'm getting the download speeds of 2000+ but my upload is topping out at 40-45mbps. I saw where people said they were getting the correct upload speeds with the Aris S33 but Comcast needed to provision the modem correctly. I've had this modem for a few years on my account, so not sure what needs to be done.

Gold Problem Solver

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26.5K Messages

20 days ago

... 2000/300 mbps plan ... upload is topping out at 40-45mbps ...

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. The few compatible retail devices are listed under the "Next Gen Speed Tier" heading 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 in the "Next Gen Speed Tier" group:

  • 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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(edited)

Visitor

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2 Messages

20 days ago

So it's just coincidental that the download speed works with the modem but the upload speed does not? Interesting.

Expert

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111K Messages

20 days ago

@Palavia 

No. It's not "coincidental". It is by design. The modem's hardware and firmware would need to be able to support the new 'mid-split' network architecture that they are in the process of deploying in order for it to be able to deliver the new Next Generation upload speeds. It currently does not.

You can Google "Comcast mid split" for more inforation.

(edited)

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