user_cab8ec's profile

Tuesday, September 19th, 2023 6:10 PM

Locked Upstream Channels


On the Xfinity gateway I was seeing at least 5 locked upstream channels. I just purchased a new Arris S33 cable modem DOCSIS 3.1 32 x 8 and I am only seeing 4 upstream locked channels and my internet is half the speed that it was or more. I am on 1000Mbps plan and I am only seeing at best 300Mbps. When I hook up the Xfinity gateway the speed is normal and getting around 850>900Mbps. I read more locked upstream channels means more speed. Does anyone know what could be going on? This is also my 5th cable modem so far in the last month trying to get speeds at least close to what they were with the Xfinity gateway. Do I need to take my Arris S33 to Xfinity to have them adjust some settings or can they do this over the coaxial cable?

Thanks for any help on this as this is getting very frustrating with losing all this speed when using my own cable modem, 5 different ones, and then plugging in Xfinity gateway to see normal speeds, or reasonably normal.


Official Employee


788 Messages

3 months ago

Greetings, @user_cab8ec! Thank you for your detailed post and for joining us here on the Xfinity Forums. You've reached the right place for help with your home network! I do see the Arris S33 is on the supported devices list and can support 1000 Mbps speeds, so we're all clear there. Have you had a chance to try the troubleshooting steps written by our amazing community experts? 

An issue with upstream signals is generally caused by wiring configurations and or splitters. Have you double-checked the cable connections when swapping out and testing the equipment? Let's also take a closer look at the Upstream and Downstream levels by viewing your modem’s status page at or​

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