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Friday, February 23rd, 2024 7:38 PM

Intermittent connection failures

I have been having intermittent failures with my connection. I have troubleshooted by using the xfinity agent, restarted / reset the modem, etc. I have no splitters or amplifiers on the cable line. The modem is a SB8200. I logged into the admin console and I see a single downstream channel that has very lower power, compared to the rest, and hundreds of thousands of uncorrectables over the last 14 days (since I reset the modem last). I've added the tables below. Any ideas?

Downstream

Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
4 Locked QAM256 435000000 Hz -0.3 dBmV 43.5 dB 1 0
1 Locked QAM256 417000000 Hz -0.1 dBmV 43.6 dB 0 0
2 Locked QAM256 423000000 Hz -0.2 dBmV 43.6 dB 4 0
3 Locked QAM256 429000000 Hz -0.3 dBmV 43.6 dB 0 0
5 Locked QAM256 441000000 Hz -0.5 dBmV 43.4 dB 1 0
6 Locked QAM256 447000000 Hz -0.7 dBmV 43.3 dB 0 0
7 Locked QAM256 453000000 Hz -0.7 dBmV 43.3 dB 0 0
8 Locked QAM256 459000000 Hz -0.7 dBmV 43.2 dB 0 0
9 Locked QAM256 465000000 Hz -0.6 dBmV 43.1 dB 11 0
10 Locked QAM256 471000000 Hz -0.6 dBmV 43.1 dB 1 0
11 Locked QAM256 477000000 Hz -0.5 dBmV 43.1 dB 0 0
12 Locked QAM256 483000000 Hz -0.6 dBmV 42.8 dB 0 0
13 Locked QAM256 489000000 Hz -0.7 dBmV 42.9 dB 1 0
14 Locked QAM256 495000000 Hz -1.0 dBmV 42.7 dB 0 0
15 Locked QAM256 501000000 Hz -1.3 dBmV 42.6 dB 0 0
16 Locked QAM256 507000000 Hz -1.5 dBmV 42.5 dB 1 0
17 Locked QAM256 513000000 Hz -1.7 dBmV 42.4 dB 0 0
18 Locked QAM256 519000000 Hz -1.8 dBmV 42.3 dB 12 0
19 Locked QAM256 525000000 Hz -1.6 dBmV 42.2 dB 18 0
20 Locked QAM256 531000000 Hz -1.5 dBmV 41.1 dB 11 0
21 Locked QAM256 537000000 Hz -1.5 dBmV 42.1 dB 0 0
22 Locked QAM256 543000000 Hz -1.6 dBmV 42.3 dB 7 0
23 Locked QAM256 549000000 Hz -1.7 dBmV 42.3 dB 11 0
24 Locked QAM256 555000000 Hz -1.9 dBmV 42.1 dB 16 0
25 Locked QAM256 561000000 Hz -2.1 dBmV 42.0 dB 17 0
26 Locked QAM256 567000000 Hz -2.3 dBmV 41.6 dB 11 0
27 Locked QAM256 573000000 Hz -2.5 dBmV 41.8 dB 9 0
28 Locked QAM256 579000000 Hz -2.6 dBmV 41.7 dB 14 0
29 Locked QAM256 585000000 Hz -2.8 dBmV 41.6 dB 10 0
30 Locked QAM256 591000000 Hz -2.9 dBmV 41.6 dB 1 0
31 Locked QAM256 597000000 Hz -2.9 dBmV 41.6 dB 1 0
32 Locked QAM256 603000000 Hz -2.9 dBmV 41.6 dB 12 0
193 Locked Other 957000000 Hz -16.4 dBmV 27.8 dB 74869046 295722069

Upstream

Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 1 Locked SC-QAM Upstream 16400000 Hz 6400000 Hz 41.0 dBmV
2 2 Locked SC-QAM Upstream 22800000 Hz 6400000 Hz 42.0 dBmV
3 3 Locked SC-QAM Upstream 29200000 Hz 6400000 Hz 42.0 dBmV
4 4 Locked SC-QAM Upstream 35600000 Hz 6400000 Hz 42.0 dBmV

Contributor

 • 

168 Messages

2 months ago

@dishawbr - Yes, your Channel ID 193 is out of specs., and depends how comfortable you are troubleshooting, you could start with the steps in this Post or another webpage if you wish.

6 Messages

Thank you for this. I've moved the modem directly to the line that comes in from the outside and the specs are roughly still the same power wise. I rebooted the modem and all my equipment after moving the modem as well. I'm not sure about the rest of the troubleshooting steps and how much they will help. Seems this might be a problem with the cable from the road?

Downstream

Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
4 Locked QAM256 435000000 Hz 3.9 dBmV 43.4 dB 0 0
1 Locked QAM256 417000000 Hz 3.9 dBmV 43.4 dB 0 0
2 Locked QAM256 423000000 Hz 3.8 dBmV 43.4 dB 0 0
3 Locked QAM256 429000000 Hz 3.9 dBmV 43.4 dB 0 0
5 Locked QAM256 441000000 Hz 3.7 dBmV 43.4 dB 0 0
6 Locked QAM256 447000000 Hz 3.5 dBmV 43.2 dB 0 0
7 Locked QAM256 453000000 Hz 3.5 dBmV 43.2 dB 0 0
8 Locked QAM256 459000000 Hz 3.5 dBmV 43.0 dB 0 0
9 Locked QAM256 465000000 Hz 3.5 dBmV 43.1 dB 0 0
10 Locked QAM256 471000000 Hz 3.5 dBmV 43.1 dB 0 0
11 Locked QAM256 477000000 Hz 3.6 dBmV 43.1 dB 0 0
12 Locked QAM256 483000000 Hz 3.5 dBmV 43.0 dB 0 0
13 Locked QAM256 489000000 Hz 3.4 dBmV 42.9 dB 0 0
14 Locked QAM256 495000000 Hz 3.2 dBmV 42.8 dB 0 0
15 Locked QAM256 501000000 Hz 3.1 dBmV 42.7 dB 0 0
16 Locked QAM256 507000000 Hz 3.0 dBmV 42.7 dB 0 0
17 Locked QAM256 513000000 Hz 2.9 dBmV 42.7 dB 0 0
18 Locked QAM256 519000000 Hz 2.8 dBmV 42.5 dB 0 0
19 Locked QAM256 525000000 Hz 2.9 dBmV 42.3 dB 0 0
20 Locked QAM256 531000000 Hz 3.0 dBmV 42.5 dB 0 0
21 Locked QAM256 537000000 Hz 2.9 dBmV 42.4 dB 0 0
22 Locked QAM256 543000000 Hz 2.8 dBmV 42.5 dB 0 0
23 Locked QAM256 549000000 Hz 2.6 dBmV 42.3 dB 0 0
24 Locked QAM256 555000000 Hz 2.4 dBmV 42.1 dB 0 0
25 Locked QAM256 561000000 Hz 2.2 dBmV 42.2 dB 0 0
26 Locked QAM256 567000000 Hz 2.1 dBmV 41.8 dB 0 0
27 Locked QAM256 573000000 Hz 2.0 dBmV 41.8 dB 0 0
28 Locked QAM256 579000000 Hz 2.0 dBmV 41.9 dB 0 0
29 Locked QAM256 585000000 Hz 1.9 dBmV 41.9 dB 0 0
30 Locked QAM256 591000000 Hz 1.8 dBmV 41.8 dB 0 0
31 Locked QAM256 597000000 Hz 1.8 dBmV 41.9 dB 0 0
32 Locked QAM256 603000000 Hz 1.8 dBmV 41.6 dB 0 0
193 Locked Other 957000000 Hz -11.1 dBmV 29.5 dB 576118551 0


Upstream

Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 1 Locked SC-QAM Upstream 16400000 Hz 6400000 Hz 37.0 dBmV
2 2 Locked SC-QAM Upstream 22800000 Hz 6400000 Hz 37.0 dBmV
3 3 Locked SC-QAM Upstream 29200000 Hz 6400000 Hz 38.0 dBmV
4 4 Locked SC-QAM Upstream 35600000 Hz 6400000 Hz 38.0 dBmV

Visitor

 • 

2 Messages

2 months ago

I am having the same problem. I've tried 2 different Gateways and 2 different runs of coax with no change. I had one Xfinity technician visit and he installed a splitter to get my signal strength down to a acceptable level. I asked him about these channel errors (corrected errors)  Motorola MG8702. I see millions of errors on channel 24 (earlier) and now I see millions of corrected errors on channel 32 for example now:

  32 Locked OFDM PLC 37 690.0 2.4 41.4 10408298 65824
 Here is examples I see over and over: SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;; No Ranging Response received - /T3 time-out SYNC Timing Synchronization failure - /Failed to acquire QAM/QPSK symbol timing;; MDD message timeout /RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;

I need to send in my event logs as they do not seem to think I have an issue so that is why I'm here this has been going on for months.

Thanks for any help or understanding,

Contributor

 • 

168 Messages

@rocky1158 - I don't think the large number of Corrected errors on OFDM PLC channel is an issue on MG8702, you will notice if you keep refreshing the Connection Tab, the numbers are constantly increasing/decreasing at the very high rate.  

32 Locked OFDM PLC 33 690.0 -1.9 42.0 2022576004 2

 

(edited)

Official Employee

 • 

898 Messages

2 months ago

Greetings, dishawbr. Thanks for reaching out to our Community Forums. Did you get a chance to try the Internet Troubleshooting Tips that

@user_noname suggested? 

 

6 Messages

I've moved the modem directly to the line that comes in from the outside and the specs are roughly still the same power wise. I rebooted the modem and all my equipment after moving the modem as well. I'm not sure about the rest of the troubleshooting steps and how much they will help. Seems this might be a problem with the cable from the road?

Downstream

Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
4 Locked QAM256 435000000 Hz 3.9 dBmV 43.4 dB 0 0
1 Locked QAM256 417000000 Hz 3.9 dBmV 43.4 dB 0 0
2 Locked QAM256 423000000 Hz 3.8 dBmV 43.4 dB 0 0
3 Locked QAM256 429000000 Hz 3.9 dBmV 43.4 dB 0 0
5 Locked QAM256 441000000 Hz 3.7 dBmV 43.4 dB 0 0
6 Locked QAM256 447000000 Hz 3.5 dBmV 43.2 dB 0 0
7 Locked QAM256 453000000 Hz 3.5 dBmV 43.2 dB 0 0
8 Locked QAM256 459000000 Hz 3.5 dBmV 43.0 dB 0 0
9 Locked QAM256 465000000 Hz 3.5 dBmV 43.1 dB 0 0
10 Locked QAM256 471000000 Hz 3.5 dBmV 43.1 dB 0 0
11 Locked QAM256 477000000 Hz 3.6 dBmV 43.1 dB 0 0
12 Locked QAM256 483000000 Hz 3.5 dBmV 43.0 dB 0 0
13 Locked QAM256 489000000 Hz 3.4 dBmV 42.9 dB 0 0
14 Locked QAM256 495000000 Hz 3.2 dBmV 42.8 dB 0 0
15 Locked QAM256 501000000 Hz 3.1 dBmV 42.7 dB 0 0
16 Locked QAM256 507000000 Hz 3.0 dBmV 42.7 dB 0 0
17 Locked QAM256 513000000 Hz 2.9 dBmV 42.7 dB 0 0
18 Locked QAM256 519000000 Hz 2.8 dBmV 42.5 dB 0 0
19 Locked QAM256 525000000 Hz 2.9 dBmV 42.3 dB 0 0
20 Locked QAM256 531000000 Hz 3.0 dBmV 42.5 dB 0 0
21 Locked QAM256 537000000 Hz 2.9 dBmV 42.4 dB 0 0
22 Locked QAM256 543000000 Hz 2.8 dBmV 42.5 dB 0 0
23 Locked QAM256 549000000 Hz 2.6 dBmV 42.3 dB 0 0
24 Locked QAM256 555000000 Hz 2.4 dBmV 42.1 dB 0 0
25 Locked QAM256 561000000 Hz 2.2 dBmV 42.2 dB 0 0
26 Locked QAM256 567000000 Hz 2.1 dBmV 41.8 dB 0 0
27 Locked QAM256 573000000 Hz 2.0 dBmV 41.8 dB 0 0
28 Locked QAM256 579000000 Hz 2.0 dBmV 41.9 dB 0 0
29 Locked QAM256 585000000 Hz 1.9 dBmV 41.9 dB 0 0
30 Locked QAM256 591000000 Hz 1.8 dBmV 41.8 dB 0 0
31 Locked QAM256 597000000 Hz 1.8 dBmV 41.9 dB 0 0
32 Locked QAM256 603000000 Hz 1.8 dBmV 41.6 dB 0 0
193 Locked Other 957000000 Hz -11.1 dBmV 29.5 dB 576118551 0


Upstream

Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 1 Locked SC-QAM Upstream 16400000 Hz 6400000 Hz 37.0 dBmV
2 2 Locked SC-QAM Upstream 22800000 Hz 6400000 Hz 37.0 dBmV
3 3 Locked SC-QAM Upstream 29200000 Hz 6400000 Hz 38.0 dBmV
4 4 Locked SC-QAM Upstream 35600000 Hz 6400000 Hz 38.0 dBmV

6 Messages

How can I provide this information to support such that they send somebody out to look at the line to the road?

6 Messages

A tech will be coming out tomorrow to check things out

Expert

 • 

103.3K Messages

@dishawbr​ 

Good luck with it !

Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it up to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home. And if the problem is found to be on their side of the demarcation point, there will not be any charge.

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.

Was your question answered? Please mark an Accepted Answer!tick

Expert

 • 

103.3K Messages

2 months ago

@rocky1158 wrote;

"I see millions of corrected errors on channel 32 for example now:"

FWIW. The OFDM channel is a very wide bandwidth channel that packs a lot of data within. Due to that fact, seeing a large number of corrected errors is normal. The FEC (Forward Error Correction) circuitry / system is doing its job. The vast majority of those errors are *corrected* ones. It's the *uncorrected* ones that can be problematic if they are numerous. 

(edited)

6 Messages

So it's normal to have high numbers of both? It's bad if the correcables are low and uncorrectables are high?

Expert

 • 

103.3K Messages

@dishawbr​ 

1) No. Just correctables.

2) Yes.

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.

Was your question answered? Please mark an Accepted Answer!tick

Visitor

 • 

2 Messages

2 months ago

OK, First off Thanks everyone for trying to help me.

The problem I'm seeing is with random video buffing on my media players (Roku's connected with ethernet cables) and all these errors on my Modem. Seems like the buffing may be occurring as these errors occur. Connection Speed is not an issue 900+Mbps most of the time. This has been going on for months now and I have had some up and down service mainly in the a.m. hours (mid morning) but the buffing problem randomly all day.

I searched for answers and some of these are upstream errors? Too much noise on the line? Too much signal strength?( which has been a problem a few times in the past) So here are a few I see I don't have the foggiest idea about:

1) Critical /SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing

2)Critical /No Ranging Response received - T3 time-out

3)Warning /MDD message timeout

4)Warning /RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW

5)Warning /Dynamic Range Window violation

6)Warning /RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW

I have a simple setup with my Modem /Gateway just on the other side of the wall where my cable comes in. I have ran 2 different (different brands) quad shielded coax (approx. 10ft runs) with Digicon connectors with no change. I have tried 2 different modems: ArrisSVG2482AC and this new MG8702 with no change. I'm seeing the buffing on more than one of my media players again connected with a CAT5 cable.

Picture me scratching my head... I always get the tough problem it seems.

Thanks again, 

Official Employee

 • 

1.1K Messages

@rocky1158 feel free to send us a direct message. There's a likely chance we need a second technician to follow up. You can use the Direct Messaging icon at the top of the page to send your name and service address to "Xfinity Support." It's next to the bell icon on the right side of the page. 

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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