U

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Wednesday, November 1st, 2023 1:32 PM

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Uncorrected codewords, T3/T4 timeouts, MDD message timeouts

We have been experiencing intermittent internet issues for days now.  We see millions of uncorrected codewords.  We have been advised to buy a new modem.  However, comcast then called, told me that they fixed a headend in our area (never coming to the house), and the problem completely went away for about 8 hours.  Now, it has started again just as before.  The agents on the phone tell me that it must be my modem again and that I need to get a new one (again).  I have a housecall scheduled.  Is there any way to get this escalated to a technician who can see what was done yesterday to fix the issue off-site.  That seems to be the key issue because it fixed the problem for 8 hours (with not a single uncorrected codeword).

Accepted Solution

Gold Problem Solver

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26.1K Messages

1 year ago

... We see millions of uncorrected codewords.  We have been advised to buy a new modem ...

It's possible that the modem is bad, but errors like this are much more often due to problems with the connection between the modem and Comcast's network or, less often, problems further upstream.

Could you post a text version of the data in the image? It isn't quite clear enough to be readable. It looks like downstream power levels are OK, but some of the SNR values are out of spec (less than 35 dB). It would also help to know:

  • Internet plan speed
  • modem model number
  • uptime
  • upstream: power levels for all channels
  • complete event log, if available (Be sure to remove or blot out any MAC addresses. Forum security processing considers them "personal information" and may prevent the event log from posting if these are present.)

Copy and pasted text is preferred over images. Be aware that, if you post any images, your message will be made Private for a time, as all images must be approved by the Forum Moderators before the messages containing them become generally visible.

If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips. If the tech who works on the problem finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit (approx $100) unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

Contributor

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25 Messages

@BruceW​ 

My plan speed is 400 Mbs.

The modem is a Motorola MB8600 (DOCSIS 3.1 ).

The uptime at the time of the screenshot was about 13 hours.  I'll post new numbers below which would be from about 20 hours.

Upstream power levels are:  Ch1: 49.3 dBmV, Ch2: 50 dBmV, Ch3: 49.8 dBmV, Ch4: 49.3 dBmV, Ch9: 46.5 dBmV.

The error numbers now are:

Channel                Lock Status         Modulation        Channel ID          Freq. (MHz)        Pwr (dBmV)       SNR (dB)                Corrected            Uncorrected

   1          Locked  QAM256             25           579.0    2.8         37.9       566075 129891

   2          Locked  QAM256             10           483.0    1.8         40.7       6727     543

   3          Locked  QAM256             11           489.0    2.8         40.8       8894     558

   4          Locked  QAM256             12           495.0    2.7         40.7       14855   915

   5          Locked  QAM256             13           507.0    2.6         40.7       32744   2407

   6          Locked  QAM256             14           513.0    2.2         40.3       48128   4299

   7          Locked  QAM256             15           519.0    2.3         36.5       67058   6124

   8          Locked  QAM256             16           525.0    1.7         40.6       96598   9497

   9          Locked  QAM256             17           531.0    2.7         39.6       126244 13739

   10       Locked  QAM256             18           537.0    2.6         35.3       165472 18842

   11       Locked  QAM256             19           543.0    1.4         40.4       227483 27837

   12       Locked  QAM256             20           549.0    2.3         40.4       269648 37097

   13       Locked  QAM256             21           555.0    2.2         35.8       319386 48137

   14       Locked  QAM256             22           561.0    2.7         40.5       330852 49716

   15       Locked  QAM256             23           567.0    2.8         40.7       435745 80091

   16       Locked  QAM256             24           573.0    2.6         40.6       509054 104613

   17       Locked  QAM256             26           585.0    1.8         40.5       760901 244614

   18       Locked  QAM256             27           591.0    2.3         40.4       887992 373747

   19       Locked  QAM256             28           597.0    2.5         40.4       1054350              631482

   20       Locked  QAM256             29           603.0    2.0         39.6       1183136              939115

   21       Locked  QAM256             30           609.0    3.0         36.7       1301964              1603817

   22       Locked  QAM256             31           615.0    2.2         39.5       1332468              2058583

   23       Locked  QAM256             32           621.0    2.3         36.6       1449048              2588908

   24       Locked  QAM256             33           627.0    2.8         40.3       2462888              3305994

   25       Locked  QAM256             34           633.0    3.0         34.6       3298354              3713342

   26       Locked  QAM256             35           639.0    3.8         35.3       4729290              4564914

   27       Locked  QAM256             36           645.0    2.7         33.3       5154360              4809788

   28       Locked  QAM256             37           651.0    3.4         40.4       4515501              4313859

   29       Locked  QAM256             38           657.0    3.1         37.7       2569017              3342840

   30       Locked  QAM256             39           663.0    2.1         40.1       1649205              2866543

   31       Locked  QAM256             40           669.0    3.5         38.5       1313023              2217162

   32       Locked  OFDM PLC           41           722.0    3.5         36.1       -1697415070     329

(apologies that some counters have rolled over...)

I cleared my event log by mistake. 

Another interesting change here is that the problems seem to have stopped again around 8:30am this morning.  Nothing was changed inside the home.  I will reset the counters to see if we start seeing problems again.  Somewhere, someone is adjusting things to fix our problem, but the front end tech support doesn't seem to know what's happening.

Accepted Solution

Contributor

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25 Messages

1 year ago

This issue finally got resolved. A line maintenance team was called by the second premise tech.  The line maintenance team identified two bad amplifiers, one had to be swapped out two blocks away and my local one had to be trimmed a bit.  Everything seems right now with better powers and Snr.

Xfinity makes it very hard to get the right people's attention. 

Contributor

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25 Messages

1 year ago

The log above was reset at 5pm last night so this is about 12 hours of recording.

Gold Problem Solver

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26.1K Messages

1 year ago

Much better, thank you. As stated, some of the SNR values are out of spec (too low), and the values are scattered in an odd way. The upstream power levels are also borderline (too high). And the error counts are, as you noted, extremely high for just a few hours of operation. Having a Comcast premise tech to attempt to straighten this out is probably the way to go. Please let us know how things turn out, and good luck!

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

Contributor

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25 Messages

@BruceW​ Since 8:30am this morning, we have seen 0 uncorrected codewords on any channel.  We have seen zero timeout messages.  Something changed somewhere because we had millions of uncorrectable errors in the prior 12 hours.  Hopefully the premise tech can help us to locate the issue. 

Contributor

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25 Messages

Everything was fine when the premise tech came onsite.  Last night when it got cold again, we started seeing the issue reoccur.  We are now seeing low SNR and lots of uncorrectables.  The premise tech suspects that it is the amplifier at the street or something upstream affected by weather, but he wasn't authorized to check that equipment.

I don't know how to get comcast's attention to this matter.

Official Employee

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1.5K Messages

Hello @user_c0244c, thank you for taking the time to reach out on social media.  I understand your concern with the connection, and I'd like the opportunity to check into that for you.

 

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