Community Forum

31 instead of 32 Channels on Docsis 3.1 Modem

Highlighted
Frequent Visitor

31 instead of 32 Channels on Docsis 3.1 Modem

I just purchased an ARRIS T25 modem for use with my 1Gb Xfinity service. Download speeds are only in the 200 - 400 Mbps range. Comcast support hasn't been able to help, including an an on-site visit.

 

I called ARRIS technical support. I was told I should have 32 downstream channels (per the modem's status page), but I have only 31. ARRIS said to let Comcast know.

 

Before I call Comcast again, I'd greatly appreciate guidance on what to say. I don't think the front-line folks will know of which I speak if I ask for 32 instead of 31 channels.

 

Thanks for your advice!

Highlighted
Expert

Re: 31 instead of 32 Channels on Docsis 3.1 Modem

O/k so FWIW, many if not most local systems offer only 31 channels now as the gigabit speed tier is supplied via the single DOCSIS 3.1 / OFDM downstream channel, not the other DOCSIS 3.0 QAM 256 downstream channels. There is some other reason that you are not getting your speed;

 

See this to start with;

 

https://forums.xfinity.com/t5/Your-Home-Network/Troubleshooting-Gigabit-internet-speeds/m-p/3145413#...



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Frequent Visitor

Re: 31 instead of 32 Channels on Docsis 3.1 Modem

Thank you very much for your informed reply!

I have reviewed the page you suggested, including the trouble-shooting tips on https://forums.xfinity.com/t5/Your-Home-Network/Xfinity-Internet-Connection-Troubleshooting-Tips/m-p....

 

I'm still at a loss as to why my download speeds are so low. If you have a moment to look at my modem's status and event log (attached), I'd greatly appreciate it.

 

Thanks again!

 

PS: Upload speeds are good, ranging up to 42 Mbps.

Highlighted
Expert

Re: 31 instead of 32 Channels on Docsis 3.1 Modem

Even though the signal stats looked o/k at that snapshot in time, the error log entries confirm that something is going on. Perhaps there is noise ingress into the line(s) somewhere.

 

There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.


I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They can check the CMTS (Cable Modem Termination System) for any real time degradation and / or error reports, see your node / cable plant and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Official Employee

Re: 31 instead of 32 Channels on Docsis 3.1 Modem

Hello, SgtHowl!

I'm glad you reached out to us for help with your Gigabit speeds. We definitely want you to enjoy your services to their fullest and I would love to take a closer look into this issue with you to make that happen. 
Please send me a private message with your first and last name as well as your service address so I can assist. 
 
 To send a private message, click my name "Comcast_Support", then click "send a message".


I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: CARE, Product, Leadership. We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!