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John523
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Saturday, August 8th, 2026 11:35 PM

Frequent Intermittent disconnects

I've had intermittent disconnects since starting service in March. I had hoped that replacing the cable from the demarc box into my house would help as the existing coax was of unknown age, but the issue has not improved. I see packet loss increase to the point where connection drops, then things improve after 10-15 minutes.

Error and uncorrectable codewords increase constantly after modem reboot, these numbers are after about a week of uptime. I've given up restarting, it doesn't reliably fix the issue or make it stay away for any length of time. What do I need to look at next?

Downstream Channel Bonding Value
Channel ID 44 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 193 194
Lock Status Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked
Frequency 645 MHz 459 MHz 465 MHz 471 MHz 477 MHz 483 MHz 489 MHz 495 MHz 501 MHz 507 MHz 513 MHz 519 MHz 525 MHz 531 MHz 537 MHz 543 MHz 549 MHz 555 MHz 561 MHz 567 MHz 573 MHz 579 MHz 585 MHz 591 MHz 597 MHz 603 MHz 609 MHz 615 MHz 621 MHz 627 MHz 633 MHz 639 MHz 722000000 957000000
SNR 43.9 dB 44.8 dB 44.7 dB 44.8 dB 44.7 dB 44.8 dB 44.7 dB 44.8 dB 44.8 dB 44.9 dB 44.9 dB 44.7 dB 44.7 dB 44.7 dB 44.7 dB 44.7 dB 44.4 dB 44.5 dB 44.5 dB 44.5 dB 44.5 dB 44.4 dB 44.2 dB 44.2 dB 44.3 dB 44.3 dB 44.2 dB 44.1 dB 44.3 dB 44.3 dB 44.2 dB 44.1 dB 44.0 dB 43.2 dB
Power Level 7.3 dBmV 7.6 dBmV 7.6 dBmV 7.6 dBmV 7.7 dBmV 7.7 dBmV 7.6 dBmV 7.7 dBmV 7.7 dBmV 7.6 dBmV 7.5 dBmV 7.5 dBmV 7.4 dBmV 7.5 dBmV 7.5 dBmV 7.4 dBmV 7.4 dBmV 7.4 dBmV 7.5 dBmV 7.5 dBmV 7.6 dBmV 7.5 dBmV 7.3 dBmV 7.3 dBmV 7.7 dBmV 7.7 dBmV 7.6 dBmV 7.7 dBmV 7.7 dBmV 7.6 dBmV 7.5 dBmV 7.3 dBmV 7.7 dBmV 5.8 dBmV
Modulation 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM OFDM

OFDM

CM Error Codewords
Channel ID 44 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 193 194
Unerrored Codewords 839408429 1538847201 1538884942 1538923498 1538973201 1539004014 1539040926 1539080340 1539415832 1539129983 1539176965 1539208443 1539245380 1539287372 1539339698 1539374409 1539544246 1539426805 1539461430 1539496162 1539537741 1539575125 1539604658 1539645679 1539702221 1539694171 1539734828 1539775978 1539845353 1539874133 1539851610 1539857066 3094159412 839408429
Correctable Codewords 163602960 64262 65202 62769 60132 61747 60625 57823 57803 58597 56005 55321 56950 53977 52457 54064 53257 49652 51329 51536 47996 48940 50513 47981 45855 48561 46637 44833 46151 46615 43240 44451 2308002301 163602960
Uncorrectable Codewords 135835 58853 60372 58265 54690 55950 55241 50834 52045 52610 49360 47329 50232 47082 45360 47051 46478 43241 43804 44862 42418 41744 42718 41077 38665 40775 39647 38731 38851 39290 36982 37143 190699 135835

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EG

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119.9K Messages

1 day ago

Please also post the upstream power level values.

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John523

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18 hours ago

Upstream Channels

Upstream Channel Bonding Value
Channel ID 1 2 3 4 41
Lock Status Locked Locked Locked Locked Locked
Frequency 16 MHz 22 MHz 29 MHz 35 MHz 36 MHz
Symbol Rate 5120 5120 5120 5120 0
Power Level 42.5 dBmV 43.0 dBmV 43.5 dBmV 44.8 dBmV 39.7 dBmV
Modulation QAM QAM QAM QAM OFDMA
Channel Type ATDMA ATDMA ATDMA ATDMA TDMA

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EG

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119.9K Messages

4 hours ago

Those are in spec. The downstream power is a tad high / borderline, but I don't think that is the cause of the problem.

There may be spurious noise ingress into the line(s) somewhere. There are other signal stat values 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 equally important in diagnosing connectivity issues as are the modem's stats.


I'm going to escalate your issue to the Comcast corporate employees (The Digital Care Team) who are available to these boards. They will be able to poll the CMTS (Cable Modem Termination System) to check 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 those upstream receive signal stats.


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

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John523

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Thank you so much for the detailed response and escalation!

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3 hours ago

EG

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119.9K Messages

@John523​ 

Quite welcome !

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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