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SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaffected.

So my SB6141 has been fine for almost two years, i'm getting 117Mbps down when its operating normally and this has been the case since TW upgraded the service. But, recently the modem has been getting into a mode where it drops the downstream to <0.5Mbps and it stays there until I power cycle the modem. This has been happening about every 5-6 days. The upstream is unaffected during this time. Spent a call with TW on this and they see nothing on their end that would indicate the modem is having problems, however their attempts to remotely reboot the modem were unsuccessful so I just power cycled it manually. Anyhow, wondering if there is a signal issue outside since nothing has changed on my end. The modem is tied to the only cable line coming into the house and no splitters. Here is the signal information:

 

Downstream

Bonding Channel Value

Channel ID

18 

19 

20 

21 

22 

24 

29 

32 

Frequency

561000000 Hz 

567000000 Hz 

573000000 Hz 

579000000 Hz 

585000000 Hz 

597000000 Hz 

627000000 Hz 

645000000 Hz 

Signal to Noise Ratio

37 dB 

38 dB 

38 dB 

38 dB 

38 dB 

39 dB 

39 dB 

39 dB 

Downstream Modulation

QAM256 

QAM256 

QAM256 

QAM256 

QAM256 

QAM256 

QAM256 

QAM256 

Power Level

The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading

4 dBmV  

4 dBmV  

4 dBmV  

5 dBmV  

5 dBmV  

6 dBmV  

7 dBmV  

6 dBmV  

 

Upstream

Bonding Channel Value

Channel ID

Frequency

24200000 Hz 

19400000 Hz 

30600000 Hz 

37000000 Hz 

Ranging Service ID

601 

601 

601 

601 

Symbol Rate

5.120 Msym/sec 

2.560 Msym/sec 

5.120 Msym/sec 

2.560 Msym/sec 

Power Level

42 dBmV 

41 dBmV 

42 dBmV 

43 dBmV 

Upstream Modulation

[3] QPSK
[1] 16QAM
[2] 64QAM
 

[3] QPSK
[2] 16QAM
 

[3] QPSK
[1] 16QAM
[2] 64QAM
 

[3] QPSK
[3] 16QAM
 

Ranging Status

Success 

Success 

Success 

Success 

 

Signal Stats (Codewords)

Bonding Channel Value

Channel ID

18 

19 

20 

21 

22 

24 

29 

32 

Total Unerrored Codewords

2639833165 

2392988823 

2393011528 

2393012520 

2392951104 

2251158763 

2151507387 

1984268451 

Total Correctable Codewords

62 

63 

245 

59 

73 

80 

1325 

903 

Total Uncorrectable Codewords

3121 

1940 

2922 

1999 

2995 

4433 

5737 

5830 

 

I also noticed i the logs a few errors which occurred on the most recent instance of this problem:

Sep 02 2016 13:57:46

5-Warning

T202.0

Lost MDD Timeout;CM-MAC=d0:39:b3:f8:37:17;CMTS-MAC=00:17:10:8b:69:11;CM-QOS=1.1;CM-VER=3.0;

Sep 02 2016 13:57:46

5-Warning

N/A

DS Partial Service Fallback: MDD Lost-> CM in DOCSIS 3.0 Recovery Mode ;CM-MAC=d0:39:b3:f8:37:17;CMTS-MAC=00:17:10:8b:69:11;CM-QOS=1.1;CM-VER=3.0;

 

If anyone has some advice I would greatly appreciate it.

 

23 REPLIES 23
Expert

Re: SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaff

Make sure all connections are a tad more than finger tight, if nothing obvious, call TWC, you've got really bad broadcast TV ingress causing the skipped channels and partial service downstream.

 

Spectrum Employee

Re: SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaff

Your issue is intermittent interruptions/disconnections in service, but the root cause is not readily apparent and most likely a simple phyical root cause.

 

You've transmitted roughly 3 TB of data on each of the 8 downstream channels your modem has locked onto, those error counts are less than 0.0001% of the total.  And those uncorrectable were from some sort of disconnection and your modem was loosing what it was transmitting, your modem basically counting errors on a communication channel that had already completely lost connectivity.

 

While I was observing your connection there for a moment, it was flowing traffic just fine with no error, then your modem just disappeared off the network entirely, and came back later.

 

So look for a sucked-out fitting (meaning, the white dielectric is receeded and not flush with the metal ring when you look down into the connector), or loose coax fitting.  That is probably the culprit. Check both inside & outside.

 

Just FYI, here's an example of a wrench that is used to train new-hires on what the correct torque is when tightening (overtightening isn't a good idea either):

 

If you are still unable to find the root cause, please call us, this may require a field tech to come out on-site for repairs.  But certainly try to see if you can find where the partial connection might be.

 

Is this an aerial or undergound service line "drop" coming to your home?  Appartment or house?

My postings on this site are my own, off-the-clock, and don’t necessarily represent TWC’s/Charter's strategies or opinions.
Spectrum Employee

Re: SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaff


@MsRaye wrote:

 you've got really bad broadcast TV ingress causing the skipped channels and partial service downstream.


Um, no that's not the cause.   If it was his/her neighbors would be also picking up echoes of the backfeed and it could be seen on the node's noise floor, and they're none of that is the case.  Please stop assuming everything is caused by broadcast TV radio ingressing on the lines.  They are supposed to be shielded to prevent any of that, and while leaks can & do happen, it's not that common.  Not everything is caused by radio station broadcast MsRaye.

My postings on this site are my own, off-the-clock, and don’t necessarily represent TWC’s/Charter's strategies or opinions.
Browser

Re: SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaff

Hello, thanks a lot for the information. This is a house and its an underground drop. In fact, it was replaced a few years back with a new orange cable as the older existing line was cut accidentally by a utility crew for something unrelated to the cable. I will examine the physical connections on the outside of the house and to the modem. I have a single coax coming from the coupler on the outside of the house up to the second floor where I extended it with another coupler. Maybe that's the cuplrit, but odd that its been fine for me for so long. Based on what you said though, maybe its not been fine and its had issues all along, but I just didn't notice them until they got worse. I'll let you know what I find.

Spectrum Employee

Re: SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaff

Please do, I'd  be interested to know what you've found. Smiley Happy

 

My postings on this site are my own, off-the-clock, and don’t necessarily represent TWC’s/Charter's strategies or opinions.
Expert

Re: SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaff

All connections must be a tad more than finger tight.  Use a couple 7/16 open end wrenches, break them loose and then retighen them.

Downstream ingress after a tapoff usually afects only that subscribers modem and cable boxes because of the isolation in the tapoffs splitter provided that the ingress point is a distance from the tapoff... If it's at the tapoff it will probably affect everyone on that tap.

Browser

Re: SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaff

Hey there, just reporting back. I removed a 6 foot section of cable between my modem and the  main line from the outside of the house. Unfortunately, about 24 hours later the modem did it again, falling back to almost nothing (for practical purposes < 0.5Mbs) and I had to reboot it again. It is now directly wired to the outside, so there is a single coupler to the line that goes underground.  Here is a paste of my signal status:

DownstreamBonding Channel Value

Channel ID

18 

21 

22 

23 

24 

28 

30 

Frequency

561000000 Hz 

579000000 Hz 

585000000 Hz 

591000000 Hz 

597000000 Hz 

621000000 Hz 

633000000 Hz 

Signal to Noise Ratio

37 dB 

38 dB 

38 dB 

38 dB 

39 dB 

39 dB 

39 dB 

Downstream Modulation

QAM256 

QAM256 

QAM256 

QAM256 

QAM256 

QAM256 

QAM256 

Power Level

The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading

4 dBmV  

4 dBmV  

5 dBmV  

5 dBmV  

6 dBmV  

7 dBmV  

6 dBmV  

 

UpstreamBonding Channel Value

Channel ID

Frequency

24200000 Hz 

19400000 Hz 

30600000 Hz 

37000000 Hz 

Ranging Service ID

4532 

4532 

4532 

4532 

Symbol Rate

5.120 Msym/sec 

2.560 Msym/sec 

5.120 Msym/sec 

2.560 Msym/sec 

Power Level

43 dBmV 

42 dBmV 

44 dBmV 

44 dBmV 

Upstream Modulation

[3] QPSK
[1] 16QAM
[2] 64QAM
 

[3] QPSK
[2] 16QAM
 

[3] QPSK
[1] 16QAM
[2] 64QAM
 

[3] QPSK
[3] 16QAM
 

Ranging Status

Success 

Success 

Success 

Success 

 

Signal Stats (Codewords)Bonding Channel Value

Channel ID

18 

21 

22 

23 

24 

28 

30 

Total Unerrored Codewords

3180600056 

2662407600 

2662447470 

2662485801 

2662370991 

2662364886 

2662391590 

Total Correctable Codewords

177 

80 

94 

232 

105 

93 

528 

Total Uncorrectable Codewords

816 

2901 

2936 

4938 

4634 

4465 

3704 

 

I'm still seeing errors and warnings in the logs:

Sep 04 2016 21:15:10

5-Warning

T202.0

Lost MDD Timeout;CM-MAC=d0:39:b3:f8:37:17;CMTS-MAC=00:17:10:8b:69:11;CM-QOS=1.1;CM-VER=3.0;

Sep 04 2016 21:15:10

5-Warning

N/A

DS Partial Service Fallback: MDD Lost-> CM in DOCSIS 3.0 Recovery Mode ;CM-MAC=d0:39:b3:f8:37:17;CMTS-MAC=00:17:10:8b:69:11;CM-QOS=1.1;CM-VER=3.0;

Sep 04 2016 19:50:40

6-Notice

I401.0

TLV-11 - unrecognized OID;CM-MAC=d0:39:b3:f8:37:17;CMTS-MAC=00:17:10:8b:69:11;CM-QOS=1.1;CM-VER=3.0;

Sep 04 2016 19:50:40

5-Warning

Z00.0

MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=d0:39:b3:f8:37:17;CMTS-MAC=00:17:10:8b:69:11;CM-QOS=1.1;CM-VER=3.0;

 

So I guess the next step is to get a tech out to look at the cable to my house? If so, how do I "bypass" the normal troubleshooting steps that they usually have you run through? I've actually already called once and they should have documented all that stuff so perhaps I can just mention that and get someone out to troubleshoot physically.

 

thanks again,

 

 

 

 

 

Expert

Re: SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaff

Modem has skipped/deleted broadcast TV ch's 30,31, 36,37,38 and 40

What's your zip code?

I need to see how many are on air in your neighborhood

 

 

Browser

Re: SB6141: Rock solid for 2 years, now downstream periodically drops to <0.5Mbps, upstream unaff

Its 27502, and we don't have a cable package. just internet.