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High Uncorrectable CM Error Codewords on Index 15, 16, and 17

MrMinto
I'm here a lot

Hello. For the last few weeks I've had a frequent packet loss, but only when gaming. I use Nvidia's Geforce NOW service, so it's basically some pretty hefty streaming. I haven't noticed any problems with Youtube or in day-to-day usage for work. I've had a tech come by twice to diagnose the problem, but it still persists.

On a whim, I decided to look into the modem's settings and logs and found the following.

 

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1833858080
2356727543
2356733952
2356739876
2356743696
2356749523
2356755548
2356761194
2356766866
2356770283
2356773646
2356778670
2356759516
2356790373
2324515497
2203368013
2356182954
2356811883
2356815626
2356821646
2356826946
2356832476
2356838105
2356841563
2356845423
2356849799
2356855469
2356862331
2356866732
2356871123
2356873404
2356872286
1833858080
1762049352
0
0
0
0
0
0
0
0
0
0
0
0
0
27625326
60283957
615900
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1762049352
35
0
0
0
0
0
0
0
0
0
0
0
0
0
4656957
81839268
7580
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
35

 

Does anyone have any advice on how I can further diagnose this problem?

 

**Labels Added**

 

 

1 ACCEPTED SOLUTION

Accepted Solutions

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

-G-
Resident Expert
Resident Expert

@MrMinto  Did you contact Tech Support (or @CommunityHelps ) to get some additional tests run on your line?  Has anything changed, for better or worse, since your last post?

 

Based on your description above, I would install the splitter/attenuator between the incoming coax feed at the point-of-entry and the coax line going to the wall place upstairs.  I would then connect a coax patch cable from the upstairs wall plate to the modem.

 

Anywhere that you have a coupler joining two coax segments together, whether it's a splitter, coax wall plate or an F81 barrel connector, that's a place where you could get noise ingress, so be sure to keep any devices that transmit in the HF, VHF and/or UHF bands away from there.

 

I'm at a loss for anything else to suggest.

View solution in original post

10 REPLIES 10

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

-G-
Resident Expert
Resident Expert

@MrMinto   From what you posted, there is a problem with a few of the DOCSIS 3.0 channels... but I don't think that those channels are actually being used.  I can't really say more because you did not post your downstream and upstream signal tables, and that is the information that we really need to assess the health of your modem's connection.

 

You also have a few uncorrectables on your downstream DOCSIS 3.1 channel, which is what should be carrying most (if not all) of your traffic.  However, this is a tiny number and really nothing to be concerned about, and the huge number of correctables on that channel is actually normal and totally fine.

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

MrMinto
I'm here a lot

Thanks for taking a look! I'm trying to figure out my packet loss issues are related to my internet, or if it's on Nvidia's side, so anything helps. All of this is a total mystery to me, but if it's OK I'd like to post the downstream/upstream signal tables.
DOWNSTREAM

23
1
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5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
24
25
26
27
28
29
30
31
32
33
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
693 MHz
279 MHz
849 MHz
855 MHz
861 MHz
579 MHz
585 MHz
591 MHz
597 MHz
603 MHz
609 MHz
615 MHz
621 MHz
633 MHz
639 MHz
645 MHz
651 MHz
657 MHz
663 MHz
669 MHz
675 MHz
681 MHz
687 MHz
699 MHz
705 MHz
711 MHz
717 MHz
723 MHz
825 MHz
831 MHz
837 MHz
843 MHz
350000000
42.8 dB
41.3 dB
42.1 dB
42.2 dB
42.5 dB
42.6 dB
42.6 dB
42.5 dB
42.5 dB
42.8 dB
42.6 dB
42.5 dB
42.3 dB
41.8 dB
29.5 dB
40.0 dB
40.8 dB
42.4 dB
42.2 dB
42.4 dB
42.3 dB
42.7 dB
42.8 dB
42.6 dB
42.7 dB
42.8 dB
42.9 dB
42.8 dB
42.2 dB
42.3 dB
42.1 dB
41.9 dB
41.3 dB
10.7 dBmV
6.6 dBmV
9.3 dBmV
9.6 dBmV
10.0 dBmV
9.5 dBmV
9.3 dBmV
9.3 dBmV
9.7 dBmV
10.4 dBmV
10.1 dBmV
9.5 dBmV
9.5 dBmV
9.5 dBmV
9.3 dBmV
9.0 dBmV
9.2 dBmV
9.7 dBmV
9.6 dBmV
9.5 dBmV
9.9 dBmV
10.6 dBmV
11.0 dBmV
10.1 dBmV
10.1 dBmV
10.3 dBmV
10.9 dBmV
10.6 dBmV
10.0 dBmV
10.1 dBmV
9.7 dBmV
9.0 dBmV
7.4 dBmV
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

 

UPSTREAM

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4
5
Locked
Locked
Locked
Locked
Locked
21 MHz
25 MHz
32 MHz
38 MHz
4 MHz
2560
5120
5120
5120
0
37.3 dBmV
37.0 dBmV
38.3 dBmV
39.0 dBmV
36.0 dBmV
QAM
QAM
QAM
QAM
OFDMA
TDMA_AND_ATDMA
ATDMA
ATDMA
ATDMA
TDMA

 

And CM Error Codewords again for good measure.

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2381439871
3230067167
3230072502
3230080682
3230084790
3230089518
3230095299
3230099438
3230104234
3230107015
3230110533
3230114667
3230096329
3230125658
3193565996
3050152141
3228685747
3230149739
3230153153
3230158983
3230163822
3230169453
3230175223
3230177582
3230182652
3230188806
3230194928
3230199677
3230203174
3230208170
3230209770
3230210834
2381439871
2271538911
0
0
0
0
0
0
0
0
0
0
0
0
0
31504169
75600133
1400920
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2271538911
35
0
0
0
0
0
0
0
0
0
0
0
0
0
5061781
92963188
56431
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
35

 

Thanks again!

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

-G-
Resident Expert
Resident Expert

@MrMinto  There are a few things that I see.  First, the power level on all the downstream channels is too high; it should average out at 0 dBmV across all channels.  Also, the power levels on the upstream side are too low; they should be in the low 40's.  Both can be fixed by adding an attenuator to the line, and your field tech(s) should have done this.  (Either that or the power levels were fine when the techs came by but Maintenance bumped them up when they tried to fix other problems in the area.)

 

The signal-to-noise ratio on your 639 MHz channel is also really bad, so there is definitely some interference/noise ingress that Rogers needs to address.

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

-G-
Resident Expert
Resident Expert

@MrMinto If you happen to have a two-way coax splitter (from a previous installation?) and a terminating cap (ships with your modem) on hand, you can craft your own attenuator: Connect the incoming Rogers coax feed to the splitter's input and connect one of the outputs to the line leading to your modem.  Connect the terminating cap to the other output on the splitter.

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

MrMinto
I'm here a lot

I do and the tech did install a splitter. I ended up moving my modem, and didn't reattach it in the same way, so that's on me. I'll do that shortly and report back.

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

MrMinto
I'm here a lot

For clarity, I did as described above with the splitter.

 

Downstream

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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
693 MHz
279 MHz
849 MHz
855 MHz
861 MHz
579 MHz
585 MHz
591 MHz
597 MHz
603 MHz
609 MHz
615 MHz
621 MHz
633 MHz
639 MHz
645 MHz
651 MHz
657 MHz
663 MHz
669 MHz
675 MHz
681 MHz
687 MHz
699 MHz
705 MHz
711 MHz
717 MHz
723 MHz
825 MHz
831 MHz
837 MHz
843 MHz
350000000
42.8 dB
41.6 dB
42.3 dB
42.2 dB
42.0 dB
42.8 dB
42.7 dB
42.6 dB
42.7 dB
42.7 dB
42.7 dB
42.5 dB
41.4 dB
38.2 dB
29.1 dB
28.1 dB
30.1 dB
42.3 dB
42.3 dB
42.4 dB
41.4 dB
42.5 dB
42.7 dB
42.8 dB
42.8 dB
42.8 dB
42.9 dB
42.7 dB
42.2 dB
42.2 dB
42.3 dB
42.1 dB
41.7 dB
7.1 dBmV
3.5 dBmV
5.7 dBmV
5.4 dBmV
5.2 dBmV
5.9 dBmV
5.9 dBmV
6.0 dBmV
6.3 dBmV
6.3 dBmV
6.2 dBmV
6.1 dBmV
5.9 dBmV
5.8 dBmV
5.7 dBmV
5.6 dBmV
5.6 dBmV
5.9 dBmV
5.8 dBmV
5.9 dBmV
6.3 dBmV
6.5 dBmV
6.8 dBmV
6.9 dBmV
6.7 dBmV
6.8 dBmV
6.8 dBmV
6.5 dBmV
5.9 dBmV
6.2 dBmV
6.0 dBmV
5.5 dBmV
4.0 dBmV
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

 

Upstream

1
2
3
4
5
Locked
Locked
Locked
Locked
Locked
21 MHz
25 MHz
32 MHz
38 MHz
4 MHz
2560
5120
5120
5120
0
39.3 dBmV
40.8 dBmV
42.3 dBmV
42.3 dBmV
39.2 dBmV
QAM
QAM
QAM
QAM
OFDMA
TDMA_AND_ATDMA
ATDMA
ATDMA
ATDMA
TDMA

 

CM Error Codewords

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14
15
16
17
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21
22
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25
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33
6379952
7703250
7707753
7712382
7716734
7721058
7725874
7730997
7735639
7740305
7742863
7747142
7751404
7756624
7647726
7410347
7770522
7775610
7780402
7784878
7788864
7794187
7798758
7803508
7808084
7813049
7817582
7822801
7827860
7832675
7834516
7836318
6379952
5718894
0
0
0
0
0
0
0
0
0
0
0
0
0
106859
260317
538
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
5718894
0
0
0
0
0
0
0
0
0
0
0
0
0
0
6680
95242
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

-G-
Resident Expert
Resident Expert

@MrMinto That's better.  Your signal levels are back within norms.

 

You said that you moved your modem.  There's nothing wrong with that ... but where is it currently connected in your home and what splitters, couples, wall plates, etc are on the signal path from the point that the Rogers line enters your home to the patch cable connecting to your modem?

 

The one other thing that you could try is to connect your gateway at the point of entry, with the attenuator/splitter in place to drop the signal levels.  If you still have problems with channels at or around 639 MHz, at least that will confirm that the interference is not coming from within your own home.

 

I would still contact Rogers (or send a private message to @CommunityHelps ) and have them run some tests on your line remotely.  I don't think that there is anything that you yourself can do about the bad SNR on that one channel or the uncorrectable errors on the D3.0 channels.

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

MrMinto
I'm here a lot

I'm not particularly familiar with the terminology, but here's how things are connected.

  1. The line from outside the house goes to an external cable box. This cable used to be on a splitter, going to a downstairs coax and an upstairs coax, but since switching to Ignite, the splitter was removed and coupled to the upstairs coax.
  2. The upstairs coax goes through my room wall (metal cover plate).
  3. Upstairs coax goes into a splitter. A output connection has a cap on it. The other has the coax cable connected to the router.

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

-G-
Resident Expert
Resident Expert

@MrMinto  Did you contact Tech Support (or @CommunityHelps ) to get some additional tests run on your line?  Has anything changed, for better or worse, since your last post?

 

Based on your description above, I would install the splitter/attenuator between the incoming coax feed at the point-of-entry and the coax line going to the wall place upstairs.  I would then connect a coax patch cable from the upstairs wall plate to the modem.

 

Anywhere that you have a coupler joining two coax segments together, whether it's a splitter, coax wall plate or an F81 barrel connector, that's a place where you could get noise ingress, so be sure to keep any devices that transmit in the HF, VHF and/or UHF bands away from there.

 

I'm at a loss for anything else to suggest.

Re: High Uncorrectable CM Error Codewords on Index 15, 16, and 17

MrMinto
I'm here a lot

Hi. Thank you for following up here, and yes, I contacted CommunityHelps, and they were able to do some tests and determine that the problem likely originates outside of the Roger's Network; so, at GFN's servers, or more likely, in the equipment between mine and theirs. Understandably, not much they can do as the tests on my line and equipment all came back optimal.

 

GFN has had me do a number of tests as well, but they've all been inconclusive, and neither I nor the Rogers tech were able to actually ping/trace-route their servers. So that portion of the route remains a mystery.

Thanks again for pointing me in the right direction. While I wasn't able to figure out the problem, I can mostly mitigate it by restarting a given game (and in doing so presumably rerouting the signal), and while a bit more time consuming, gets me to minimally disruptive packet/frame loss.

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