4 Messages

Monday, February 16th, 2026 5:08 PM

Ongoing Uncorrectable Errors & T3 Timeouts – Mid-Split/High-Split – CM3000

Hello,

I am seeking assistance with intermittent connectivity drops and high packet loss on my Netgear Nighthawk CM3000. I am located in a Massachusetts market that recently underwent the "Next Generation" network upgrade (Mid-Split/High-Split).

The Issue:
Despite a recent technician visit confirming "good" levels, my modem logs are recording thousands of Uncorrectable Codewords within short windows (3+ hours). Specifically, I am seeing heavy ingress/noise concentrated in the 500MHz range (Channels 20-32) and the OFDM channel (194).

Current Signal Stats (without padding):

  • Downstream Power: Average +7.5 to +10.5 dBmV (Approaching overdriven levels).

  • Upstream Power (OFDMA): 32.3 dBmV. This appears too low to maintain a stable handshake with the CMTS, likely triggering the frequent T3 Time-outs in my Event Log.

  • SNR: 41-42 dB.

  • Error Rate: 8,000+ Uncorrectables on Channel 20 in under 4 hours.

Can an Official Employee please check the node health and look for Upstream Receive Power or Codeword Error Rates at the CMTS for my MAC? This looks like a "Main Drop" or "Tap" issue rather than an indoor wiring problem.

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Official Employee

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180 Messages

2 months ago

 

Hello user_9fiucx thanks for reaching out on our Xfinity Forums. We'd like to do everything we can to help.

Please send a direct message including your name and address, and we can get started anytime.

How to Send Us a Direct Message:

  1. Click "Sign In" if necessary.
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  3. Click the "New message" (pencil and paper) icon.
  4. In the "To:" line, type "Xfinity Support".
  5. As you type, a drop-down list will appear. Select "Xfinity Support" from that list.
  6. An "Xfinity Support" graphic will replace the "To:" line.
  7. Type your message in the text area near the bottom of the window.
  8. Press Enter to send it.

For an example of how to send us a Direct Message, check out this link.

https://forums.xfinity.com/conversations/email/cant-create-a-new-email-address/605e52b726aa974d6303…

 
 

 

Expert

 • 

117.6K Messages

2 months ago

@user_9fiucx @XfinityAbel 

Please circle back here and post any possible solutions for the issue here in these open public forums so that all readers here may benefit from the exchange / info. This is in keeping with the spirit for which these public help forums were originally intended. Thank you.

Frequent Visitor

 • 

14 Messages

@EG​ That's the last thing Comcast wants. That's why they have their hidden take it to DM mentality unfortunately.

4 Messages

22 days ago

Hey, circling back. The solution it seems was to swap my netgear for a Comcast XB8. In the process of getting the rental modem, someone thought they were doing me a favor and in fact messed up my plan. I was on a weird 1Gbps down 250Mbps up plan, now I spend 100% more money for 2Gbps down and 250Mbps up but it seems to be working better. I had asked for an X10 survey so who knows. 

Official Employee

 • 

3.3K Messages

Hello, @user_9fiucx sorry to hear the new plan is not what you anticipated. I would be happy to review your account for solutions to this. I can also submit that Gig X10 survey for you. Could you please send our team a direct message with your full name and full address? To send a direct message:

1. In the top right corner, you'll see a little chat icon near the bell icon. Click the direct message icon

2. Click the "New message" (pencil and paper) icon

3. In the 'To' line, type "Xfinity Support" there. A drop-down list appears. Select "Xfinity Support" from that list (an "Xfinity Support" graphic replaces the "To:" line)

4. Type your message in the text area near the bottom of the window

5. Press Enter to send it. An official employee, such as myself or whoever is first available, will respond. Thanks!

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