Visitor
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6 Messages
Need Tier 2 Support – S33 Modem Provisioning Error (Upload Stuck at 5 Mbps)
Hello, this is my first time posting here. I’m a long-time Xfinity customer (10+ years in the same location) and until now I’ve had consistently excellent service. I work with large files daily, so both download and upload performance are critical.
Recently, after a home remodel, I needed to relocate my office to an area where neither WiFi nor Ethernet reached. I visited an Xfinity store for guidance and was advised to use Extended Pods. I was also told my plan would be discounted. The only requirement I stressed was that I needed to maintain separate SSIDs (specifically 2.4 GHz for IoT), and I was assured this would work.
After installing the Pods, my SSIDs were automatically combined, and I learned that Xfinity Pods require a unified network. That part was my misunderstanding, so we returned them.
At this point, since I believed I had been using my own equipment for years, I discovered we had actually been paying for the Xfinity gateway all along. Wanting better coverage and more flexibility, we purchased our own equipment:
Arris Surfboard S33 (DOCSIS 3.1, Hardware v3)
TP-Link BE9300 Router
This is where the problems began.
The Issue: S33 Will Not Provision Correctly
We attempted provisioning the modem six times. Each time:
Download speeds ranged from 300–500 Mbps
Upload remained capped at ~5 Mbps
We spent 5 hours on chat, then two more hours the next day, and one hour on the phone, and kept receiving the same scripted explanation:
“The S33 is not compatible with high upload speeds and you must use an Xfinity modem.”
This conflicted with both Xfinity’s own approved device list and the FCC requirement to support customer-owned DOCSIS 3.1 modems on tiers up to 2 Gbps. I repeatedly asked to be transferred to Tier 2 for manual bootfile correction, but the agents refused and instead promoted Xfinity Mobile.
Eventually, after pressing for escalation, Loyalty routed us to a highly knowledgeable Tier 2 technician in India. He immediately identified the issue:
Xfinity’s system is detecting our S33 v3 as DOCSIS 3.0 instead of DOCSIS 3.1.
This would explain:
Failed provisioning attempts
Incorrect bootfile assignment
Upload capped at legacy 5 Mbps
He confirmed the modem is valid, opened a case, and gave us a ticket number (CR236254821). He said the backend team needed to fix the database mismatch and would call us back within 24 hours.
Unfortunately, it has now been two days with no follow-up.
After rebooting the modem today, performance became worse:
Download: 125 Mbps
Upload: 5 Mbps
We attempted to contact support again to check the case status, but the conversation repeatedly redirected toward Xfinity Mobile instead of addressing the ticket.
What We Need
I’m simply looking for:
A Tier 2 or higher technician who can correct the provisioning/bootfile issue.
Confirmation whether the S33 (Hardware v3) is fully supported for both downstream and upstream on our plan.
Proper activation of DOCSIS 3.1 upload channels (OFDMA).
We are loyal customers, and our goal is not to complain—just to get the equipment properly recognized and provisioned so we can return to work.
Any help from an Xfinity employee or someone familiar with this provisioning mismatch would be greatly appreciated.
Thank you.
XfinityMarcus
Official Employee
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2K Messages
1 day ago
user_hhxnn6 thank you for using the Xfinity Community Forums to reach out. I am happy to assist you with your technical concerns. Let's see what we can do to ensure you have the coverage you need. Can you send me a direct message with your full name and complete service address to get started?
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BruceW
Gold Problem Solver
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26.9K Messages
1 day ago
This is correct. Follow the "See all modems" link near the bottom of https://www.xfinity.com/support/internet/customerowned, and then under the "Compatible modems for enhanced speeds" heading click the Arris list. The S33 is not on it. Using devices on Internet speed tiers for which they are not compatible with tends to produce unexpected results, often speeds well below the ones you are paying for.
AFAIK Comcast/Xfinity has never said how they provision devices operating on speed tiers they're not compatible with. All I can tell you is that many customers who tried it have reported that they don't get full speed. There's a tendency to think the device will operate at the maximum speed it is capable of, but that doesn't seem to be the case. Instead, incompatible devices often seem to be provisioned to run at speeds well below what they should be capable of.
Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.
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XfinityDemitrius
Official Employee
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2.3K Messages
1 day ago
Hey @user_hhxnn6, Thank you for visiting our official Xfinity Forums Community support page. To assist, the Arris S33 is not a supported modem for our Next Generation Enhanced Internet speed plans. As a result, the modem is not going to be properly provisioned as it is an unsupported device and be provided with a default Internet configuration. You can learn about all the supported modems by visiting our 'Find other modems that work with Xfinity services' device support page. When you select the "All Modems" link, you will see a section for the 'Compatible modems for enhanced speeds' which will be needed to properly provision the device. Only the Arris G20, G34, G36, G54, and S34 are supported.
Do you still have possession of the Xfinity xFi Gateway? As an alternative, you can continue to use the Xfinity xFi Gateway and enable Bridge Mode which would disable the router functionality to continue to use the recently purchased TP-Link router. Until a supported modem is listed for the speed tier, the speeds will be decreased.
Alternative, depending on the speed tier, we can assist in downgrading the services to a supported speed tier to continue using the purchased equipment. You can view the available speed tiers for your area by visiting the 'Xfinity Broadband Nutrition Labels' support page.
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user_hhxnn6
Visitor
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6 Messages
5 hours ago
Thank you to everyone who commented and tried to help. I wanted to post a full update so others who hit the same wall can follow what we did to get everything back online.
This was not the smoothest process because we were under time pressure (my daughter only had a 30-minute lunch break and I used 45 minutes of it). Her employer was understanding — I, however, was sweating bullets.
Here’s What We Ended Up Doing (Step-By-Step for Anyone Stuck Like We Were)
1. Removed the S33 and reinstalled the XB8
We pulled the Arris S33 3.1 v3 modem and connected the XB8 gateway again. Oddly, after physical connection, the XB8 didn’t immediately broadcast a signal. We had to manually press the reboot button on the back before anything happened.
Once it restarted, it showed up properly in the Xfinity app and we were able to proceed.
2. Activated the XB8 through the Xfinity App
The app brought the XB8 online and automatically created a temporary SSID.
I changed the settings to allow local admin access so I could get into the 10.0.0.1 page and enable Bridge Mode.
Unnecessary Mistake on my part:
I was doing this on my older 2019 MacBook Pro, which does NOT have an Ethernet port, so I was doing all of it over WiFi.
When I clicked Enable Bridge Mode, it did the normal 90-second countdown — and then everything completely locked up and went offline. (DUH)
The workaround:
I connected to the unsecured “xfinitywifi” hotspot long enough for the bridge mode change to finish, but the XB8 never rebooted automatically.
3. Manual reboot of both devices
We had to manually reboot both the XB8 and TP-Link router. After rebooting both, the TP-Link came online through port 4 and everything started working normally again.
Speed Test Results:
I know my internet plan is 2000/300, but I also understand device limits. Here's what we saw:
MacBook Pro (2019), about 10 feet from the router - 598.2 Mbps down - 75.9 Mbps up
Totally expected based on this Mac’s older WiFi hardware.
2025 iPad (WiFi 6E), ~3 feet from the modem/router
Tested each SSID separately:
2.4 GHz - 104.3 Mbps down - 47.4 Mbps up
5 GHz - 1110.7 Mbps down - 64.5 Mbps up
6 GHz - 1059.2 Mbps down - 70.2 Mbps up
Not bad at all. These are close to real-world ceiling ranges for WiFi 6E. We haven’t tested a combined SSID yet — saving that for later.
Next Step
We’re going to leave the system exactly as-is for the next 3–5 days to make sure everything is stable. After that, we will install the Arris S34, verify provisioning, and return the XB8.
I’m very curious to see:
What changes in upload speed
Whether manual provisioning actually resolves our original issue
How the TP-Link behaves with the new modem
I’ll update the thread again once the S34 is installed.
If this helps even one other person avoid the same confusion we went through… totally worth posting. Thanks again to everyone assisting — more updates coming soon.
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