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user_168e86
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Thu, Jun 23, 2022 1:21 PM

Intermittent connection issues

I've been having intermittent connection issues for at least the  past 6 months. Comcast support has been playing "The IT crowd" tape: "Have You Tried Turning It Off And On Again?" throughout this time, so I though I may ask the community for any help before stopping the service.

To make sure that the problem is not from my end I have tried the following:

 * The issue appears in all computers  and mobile device (8 in total) on the connection and across three different Operating Systems

* Two different modem/routers (Nighthawk AX6 and MG8725)

 * Wifi, different Ethernet cable

 * different co-axial cables between modem and wall socket

I believe the problem is on the Upstream. Any suggestions are more than welcome.

The following is from the MG8725 modem/router after 25 minutes from a restart:

Downstream:

 Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
   1 Locked 256 QAM 17 531.0 4.1 41.2 1 0
   2 Locked 256 QAM 13 507.0 3.3 40.8 0 0
   3 Locked 256 QAM 14 513.0 3.4 41.1 0 0
   4 Locked 256 QAM 15 519.0 3.6 41.2 0 0
   5 Locked 256 QAM 16 525.0 3.9 41.2 0 0
   6 Locked 256 QAM 18 537.0 3.5 41.2 0 0
   7 Locked 256 QAM 19 543.0 2.8 41.1 0 0
   8 Locked 256 QAM 20 549.0 2.1 40.6 0 0
   9 Locked 256 QAM 21 555.0 2.0 40.7 0 0
   10 Locked 256 QAM 22 561.0 2.3 40.6 0 0
   11 Locked 256 QAM 23 567.0 2.2 40.7 0 0
   12 Locked 256 QAM 24 573.0 1.8 40.6 0 0
   13 Locked 256 QAM 25 579.0 1.7 40.5 0 0
   14 Locked 256 QAM 26 585.0 1.8 40.5 0 0
   15 Locked 256 QAM 27 591.0 1.8 40.6 0 0
   16 Locked 256 QAM 28 597.0 1.3 40.4 0 0
   17 Locked 256 QAM 29 603.0 0.8 40.2 0 0
   18 Locked 256 QAM 30 609.0 0.3 40.1 0 0
   19 Locked 256 QAM 31 615.0 0.5 40.0 1 0
   20 Locked 256 QAM 32 621.0 1.0 40.0 0 0
   21 Locked 256 QAM 33 627.0 1.2 39.9 1 0
   22 Locked 256 QAM 34 633.0 1.4 39.9 0 0
   23 Locked 256 QAM 35 639.0 1.8 39.7 0 0
   24 Locked 256 QAM 36 645.0 1.7 39.8 1 0
   25 Locked 256 QAM 37 651.0 1.1 39.7 1 0
   26 Locked 256 QAM 38 657.0 1.1 39.5 0 0
   27 Locked 256 QAM 39 663.0 1.6 39.5 0 0
   28 Locked 256 QAM 40 669.0 2.0 39.8 0 0
   29 Locked 256 QAM 41 675.0 1.5 39.2 0 0
   30 Locked 256 QAM 42 681.0 0.7 39.5 0 0
   31 Locked 256 QAM 43 687.0 0.5 39.3 0 0
   32 Locked 256 QAM 44 693.0 0.9 39.4 0 0
   33 Locked OFDM 159 702.0 2.0 39.9 4303473 0

 

Upstream:

  Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
   1 Locked SC-QAM 2 5120 16.4 37.8
   2 Locked SC-QAM 3 5120 22.8 37.8
   3 Locked SC-QAM 4 5120 29.2 39.3
   4 Locked SC-QAM 5 5120 35.6 39.8
   5 Locked SC-QAM 6 2560 40.4 40.8

Partial Logs:

07:05:01
Thu Jun 23 2022		   Critical(3)   SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    07:05:02
Thu Jun 23 2022		   Warning(5)   DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1

Question

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Updated 

Il y a 1 m

 • Edited

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EG

Expert

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95K Messages

Il y a 2 m

Please post the balance of those error log entries in their entirety (copy and paste them, don't post a screenshot) but redact the CM MAC and the CMTS MAC addresses for your privacy. They are considered to be personal information. The posting of personally identifying information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publically.

0

user_168e86

Visitor

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5 Messages

Il y a 2 m

   Time    Priority    Description 
    07:05:01
Thu Jun 23 2022   Critical(3)   SYNC Timing Synchronization failure - Loss of Sync;CM-QOS=1.1;CM-VER=3.1;
    07:05:02
Thu Jun 23 2022   Warning(5)   DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-QOS=1.1;CM-VER=3.1;
    09:42:58
Thu Jun 23 2022   Warning(5)   RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-QOS=1.1;CM-VER=3.1;
    09:42:58
Thu Jun 23 2022   Warning(5)   Dynamic Range Window violation
    09:42:58
Thu Jun 23 2022   Warning(5)   RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-QOS=1.1;CM-VER=3.1;
    09:42:58
Thu Jun 23 2022   Warning(5)   Dynamic Range Window violation
    09:42:59
Thu Jun 23 2022   Warning(5)   RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-QOS=1.1;CM-VER=3.1;
    09:42:59
Thu Jun 23 2022   Warning(5)   Dynamic Range Window violation
    09:42:59
Thu Jun 23 2022   Warning(5)   RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-QOS=1.1;CM-VER=3.1;
    09:42:59
Thu Jun 23 2022   Warning(5)   Dynamic Range Window violation
    09:43:19
Thu Jun 23 2022   Critical(3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.1;
    09:43:20
Thu Jun 23 2022   Warning(5)   RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-QOS=1.1;CM-VER=3.1;
    09:43:20
Thu Jun 23 2022   Warning(5)   Dynamic Range Window violation

2

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XfinityChristy

Official Employee

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176 Messages

@user_168e86 Thank you for reaching out via our Xfinity Forums and providing your connection history. To check in connection on our end like EG has described please send a Peer to peer message with your full name and address. 

 

To send a "Peer to peer" message:
Click "Sign In" if necessary
• Click the "Peer to peer chat" icon
• Click the "New message" (pencil and paper) icon
• Type "Xfinity Support" in the "To:" line and select "Xfinity Support" from the drop-down list which appears. The "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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Il y a 2 m

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XfinityChristy

Official Employee

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176 Messages

Thank you, please don't reboot again at this time. Once I am able to locate your account I will be able to review your Upstream Signals and find the best course of action. Please use the steps below to send me a Peer to peer message with your full name and address. 

 

To send a "Peer to peer" message:
Click "Sign In" if necessary
• Click the "Peer to peer chat" icon
• Click the "New message" (pencil and paper) icon
• Type "Xfinity Support" in the "To:" line and select "Xfinity Support" from the drop-down list which appears. The "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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Il y a 2 m

0

EG

Expert

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95K Messages

Il y a 2 m

O/k so 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) / an upstream channel / return path impairment 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 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 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 poll for those upstream receive signal stats.

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

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user_168e86

Visitor

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5 Messages

Il y a 2 m

Here is an update two and half hours after the previous stats (three hours after reboot)

 Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
   1 Locked 256 QAM 17 531.0 2.7 41.2 142 123
   2 Locked 256 QAM 13 507.0 1.8 40.8 148 120
   3 Locked 256 QAM 14 513.0 2.0 41.1 164 127
   4 Locked 256 QAM 15 519.0 2.2 41.1 176 116
   5 Locked 256 QAM 16 525.0 2.5 41.1 110 137
   6 Locked 256 QAM 18 537.0 2.1 41.1 170 93
   7 Locked 256 QAM 19 543.0 1.4 41.0 169 116
   8 Locked 256 QAM 20 549.0 0.7 40.5 125 139
   9 Locked 256 QAM 21 555.0 0.6 40.7 121 100
   10 Locked 256 QAM 22 561.0 0.9 40.6 91 86
   11 Locked 256 QAM 23 567.0 0.7 40.6 118 87
   12 Locked 256 QAM 24 573.0 0.4 40.6 152 90
   13 Locked 256 QAM 25 579.0 0.3 40.6 129 92
   14 Locked 256 QAM 26 585.0 0.4 40.3 124 75
   15 Locked 256 QAM 27 591.0 0.4 40.6 119 79
   16 Locked 256 QAM 28 597.0 0.0 40.3 106 95
   17 Locked 256 QAM 29 603.0 0.4 40.3 104 89
   18 Locked 256 QAM 30 609.0 0.8 40.1 43 61
   19 Locked 256 QAM 31 615.0 0.8 39.9 85 84
   20 Locked 256 QAM 32 621.0 0.5 39.9 113 85
   21 Locked 256 QAM 33 627.0 0.3 39.6 100 66
   22 Locked 256 QAM 34 633.0 0.0 39.7 141 78
   23 Locked 256 QAM 35 639.0 0.5 39.5 93 76
   24 Locked 256 QAM 36 645.0 0.4 39.8 76 91
   25 Locked 256 QAM 37 651.0 0.2 39.6 122 58
   26 Locked 256 QAM 38 657.0 0.2 39.6 49 83
   27 Locked 256 QAM 39 663.0 0.4 39.5 51 46
   28 Locked 256 QAM 40 669.0 0.7 39.7 39 58
   29 Locked 256 QAM 41 675.0 0.2 39.5 72 63
   30 Locked 256 QAM 42 681.0 0.6 39.5 49 61
   31 Locked 256 QAM 43 687.0 0.8 39.2 41 69
   32 Locked 256 QAM 44 693.0 0.4 39.4 45 53
   33 Locked OFDM 159 702.0 0.8 39.8 53200661 29

  Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
   1 Locked SC-QAM 2 5120 16.4 39.8
   2 Locked SC-QAM 3 5120 22.8 39.8
   3 Locked SC-QAM 4 5120 29.2 41.3
   4 Locked SC-QAM 5 5120 35.6 42.3
   5 Locked SC-QAM 6 2560 40.4 42.8

0

0

user_168e86

Visitor

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5 Messages

Il y a 2 m

12 hours after reboot

 Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
   1 Locked 256 QAM 17 531.0 4.7 41.4 3331 6050
   2 Locked 256 QAM 13 507.0 3.8 41.1 3925 6290
   3 Locked 256 QAM 14 513.0 3.8 41.3 3836 6429
   4 Locked 256 QAM 15 519.0 4.1 41.3 4038 6456
   5 Locked 256 QAM 16 525.0 4.5 41.3 3722 6620
   6 Locked 256 QAM 18 537.0 4.1 41.3 3446 6053
   7 Locked 256 QAM 19 543.0 3.4 41.3 3311 6155
   8 Locked 256 QAM 20 549.0 2.7 40.7 3357 5962
   9 Locked 256 QAM 21 555.0 2.6 41.0 3345 5540
   10 Locked 256 QAM 22 561.0 2.8 41.0 3123 5352
   11 Locked 256 QAM 23 567.0 2.6 40.9 3019 5267
   12 Locked 256 QAM 24 573.0 2.3 40.7 3007 5253
   13 Locked 256 QAM 25 579.0 2.2 40.7 3038 5212
   14 Locked 256 QAM 26 585.0 2.3 40.7 3036 4908
   15 Locked 256 QAM 27 591.0 2.3 40.8 2975 4860
   16 Locked 256 QAM 28 597.0 1.8 40.5 3367 5057
   17 Locked 256 QAM 29 603.0 1.3 40.3 3186 5196
   18 Locked 256 QAM 30 609.0 0.8 40.1 2925 5070
   19 Locked 256 QAM 31 615.0 1.1 40.2 3021 4898
   20 Locked 256 QAM 32 621.0 1.7 40.1 2995 4975
   21 Locked 256 QAM 33 627.0 1.9 39.9 2759 5200
   22 Locked 256 QAM 34 633.0 2.1 39.9 2944 5576
   23 Locked 256 QAM 35 639.0 2.6 39.8 2603 4967
   24 Locked 256 QAM 36 645.0 2.4 40.0 2573 4913
   25 Locked 256 QAM 37 651.0 1.8 39.8 2599 4919
   26 Locked 256 QAM 38 657.0 1.8 39.7 2671 4970
   27 Locked 256 QAM 39 663.0 2.3 39.6 2508 4619
   28 Locked 256 QAM 40 669.0 2.6 39.9 2488 4240
   29 Locked 256 QAM 41 675.0 2.0 39.3 2436 4526
   30 Locked 256 QAM 42 681.0 1.3 39.6 2404 4434
   31 Locked 256 QAM 43 687.0 1.0 39.4 2501 4332
   32 Locked 256 QAM 44 693.0 1.5 39.5 2523 4160
   33 Locked OFDM 159 702.0 2.6 40.0 222554875 2315

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
   1 Locked SC-QAM 2 5120 16.4 38.8
   2 Locked SC-QAM 3 5120 22.8 38.8
   3 Locked SC-QAM 4 5120 29.2 40.3
   4 Locked SC-QAM 5 5120 35.6 41.3
   5 Locked SC-QAM 6 2560 40.4 42.3

2

0

XfinityKrystal

Official Employee

 • 

181 Messages

I appreciate the information provided. In order to better assist we will need to have you send our team a peer to peer message. Please follow the steps above from my colleague and once received we will dive right in. You are in good hands. Please let us know if you run into any trouble. 

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

Like

Reply

Il y a 2 m

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user_168e86

Visitor

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5 Messages

Xfinity support suggested that a technician comes for the Nth+1 time to check the connection.

I declined as the N+1 person will highly likely have the same impact as the rest, none, and I will be changed again for the visit. My planned solution is to change providers.

Good luck to the rest of you.

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Il y a 1 m

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