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skered
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12 Messages

Tuesday, February 3rd, 2026 1:13 AM

signal issues cable modem

My modem is consistently showing issues isolated to two downstream channels.
Channel ID 42 is accumulating uncorrectable errors rapidly, and Channel ID 43 is accumulating corrected errors at a much higher rate than all other channels.
Every other downstream channel remains clean and stable, and my upstream levels are normal.
I’m connected directly from the wall to the modem, so this isn’t an inside‑wiring issue.
It appears to be a localized impairment affecting only those two channels.
Could you check the line on your side to verify signal quality for those channel IDs?

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4 months ago

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EG

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4 months ago

Are you actually experiencing any connection problems ?

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skered

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12 Messages

Today no.  However, the modem did restart yesterday afternoon that's when I started reading/researching the uncorrectable counts.

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4 months ago

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skered

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And as of less than 24 hours after that reboot.  Channels 42, 43, and 44 have 3173324, 1074205, and 30530 uncorrected counts.

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4 months ago

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EG

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4 months ago

Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers, and the correctable and uncorrectable bit errors and paste them into your next post.

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EG

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4 months ago

This may or may not be the root cause of the problem (YMMV), but it should be addressed regardless.


The downstream power is too high / out of spec. It may be overdriving the front-end receiver circuit of the modem. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.


Is there a drop amplifier on the coax cable line leading to the modem ? If so, try removing / bypassing it and see. If not, you can try installing a -6 attenuator pad such as this one on the coax port on the rear of the modem to knock that power level down and see;

https://www.amazon.com/6db-Attenuator-Pad-1-each/dp/B0013L48XA 

I don't see any channels 42, 43, or 44 listed there ? 

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skered

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12 Messages

In Downstream Overview. The last column.  Channel ID.  

(edited)

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4 months ago

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skered

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There is not adrop amplifier attached.  This is directly connected from the wall to the modem.

Is there any reason this can't be addressed at the tap/outside?

(edited)

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4 months ago

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EG

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@skered wrote;​

In Downstream Overview. The last column.  Channel ID.  

I overlooked it. My bad. Sorry...

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.

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4 months ago

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EG

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4 months ago

You can go the tech visit route if you so choose. Good luck !

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skered

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4 months ago

I'd assume Xfinity should be able to do an init. triage here?   Can we get a CC* member to comment here?

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XfinityJohnG

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Thank you for reaching out here, and providing all the information to @EG already. I will be happy to take a closer look into your issue. Can you send me a direct message with the full name and complete address for your service? 

To send a direct message [private message]:

   Click the "Direct Message" icon or  https://forums.xfinity.com/direct-messaging

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

   The "To:" line prompts you to "Type the name of a person". Instead, type "Xfinity Support" there.

   - As you are typing a drop-down list appears. Select "Xfinity Support" from that list.

   - An "Xfinity Support" graphic replaces the "To:" line.

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

   Press Enter to send it

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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4 months ago

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