J

Thursday, March 13th, 2025 8:16 AM

Poor video quality and low upload speed

I have an internet plan with 400 Mbps download speed and 150 Mbps upload speed. I was using the Xfinity Gateway XB7 and got 342 Mbps download speed and 143 Mbps upload speed. My free rental plan expired, so I bought two modems and a router to avoid monthly rental fees. I bought an Arris SB8200 and a Motorola MB8600 (both DOCSIS 3.1). I wanted to try each modem to see which was better, and return the other. The router is a TP Link AX1800 Archer AX21.

On Saturday night, I replaced the Xfinity gateway with the Arris SB8200 and the TP Link router. My internet download speed was 350 Mbps, but my upload speed was 5.5 Mbps. I tried watching a movie and the quality was much worse than with the Xfinity Gateway. The video kept buffering, and it was more pixelated. I tried YouTube videos too, and my youtube quality settings were automatically reduced to 720, so I had to adjust the settings to 1080, but the quality stayed the same bad quality. 

On Sunday I tried the Motorola MB8600, but I got the same speeds. 350 Mbps download speed and 5.5 Mbps upload speed. It looks like 6 Mbps is the max upload speed I'll get. The video quality was still poor, compared to what it was with the Xfinity Gateway XB7. I tried plugging my computer directly using an ethernet cable, and I still got 6 Mbps upload speed. I went back to the Xfinity Gateway XB7 and I had 350 Mbps download speed and 140 upload speed. Videos looked great.

On Monday, I tried the Arris SB8200 again, but this time I got 85 Mbps download speed and 6 Mbps upload speed. For some reason my download speed was greatly reduced. Still 6 Mbps upload speed. I had it on all day, and on Tuesday, I decided to try the Motorola. The Motorola gave me 400 Mbps download speed, and 6 Mbps upload speed. For some reason, the Motorola seems to still give fast download speed, but the Arris does not anymore.

I contacted Xfinity, and they tried applying "provisions" but they said my devices can't handle faster speeds. I'm a bit confused, because these two modems are both on the list of compatible devices. I guess I might need to buy one of the "recommended" devices? I read that a lot of people have had the same issue of only getting 6 Mbps upload speed. Is that the reason my video streaming quality isn't as good? 

If anyone has any advice or recommendations, I would appreciate it. I'm thinking I'll try to find a deal on one of the recommended modems. Thanks in advance.

Gold Problem Solver

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26.3K Messages

1 month ago

Neither the SB8200 nor the MB8600 are rated by them for the faster upload speeds introduced in 2023. For that 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 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/2024.09.18%20Full%20List%20of%20Compatible%20Devices.pdf, but this changes from time to time):

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

But both the SB8200 and the MB8600 should easily deliver the subscribed download speeds up to 900 Mbps and the "classic" upload speeds. The most common reason for slow speeds is not "devices can't handle", it's poor signal quality on the coax line.

If an employee does not respond to your message here, suggest you call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. It's not likely they can fix the problem remotely. If not, insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit (approx $100) unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

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.

(edited)

3 Messages

Thanks for the response! I am totally fine with getting “classic” upload speeds. 

I do not have any splitters or anything on the coax. It’s the same as when they installed it two years ago. Hopefully they won’t charge me $100. 

Thanks so much for your insight!

-Joe

3 Messages

Just wanted to follow up. I finally was able to speak to a real person on the phone. I spent all week on the online Xfinity Text Chat, chatting with agents who kept telling me that my device wasn’t able to handle fast upload speeds. On the phone today, I told the gentleman that I don’t necessarily need 150 Mbps upload speed, but I should have more than 5Mbps upload speed. Immediately, he said he understood. Instead of telling me that my device wasn’t compatible, he told me to unplug my router while he reset my modem. He ran a reset, then tried to get me to sign up for a free cell phone line haha, and after my modem booted, I plugged in my router. The router fully booted on and BOOM my internet upload speed was 40Mbps!!! Download speed still great at 400Mbps. 
Thanks for your help BruceW!
I just wish I was able to speak to someone on the phone sooner. I tried but they kept directing me to a text that linked to the online chat assistant. Finally someone called me today, and this was all fixed in 15 minutes 🤷🏼‍♂️

Official Employee

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3.1K Messages

Thank you for that update @joenobodyyet Is there anything I may assist you with at this time?

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
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