Spectator

Internet cutting out multiple times a day

I have my own Surfboard SB6121 modem which has worked perfectly for a couple years but the past 6 months the internet will intermittently drop for 10-20 seconds  3-4 times a day. here are some logs

 

Time Priority Code Message
Apr 12 2018 08:59:483-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 10 2018 16:13:283-CriticalT05.0SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 10 2018 16:13:273-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 10 2018 10:50:463-CriticalT05.0SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 10 2018 09:57:053-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 10 2018 09:56:483-CriticalR04.0Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 10 2018 09:56:413-CriticalT05.0SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 10 2018 07:03:503-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 09 2018 13:44:343-CriticalT05.0SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 09 2018 04:48:003-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 09 2018 04:47:403-CriticalT05.0SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 08 2018 11:58:083-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 08 2018 11:57:533-CriticalR04.0Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 08 2018 11:57:483-CriticalT05.0SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 08 2018 07:19:563-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 07 2018 19:06:383-CriticalT05.0SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 07 2018 18:53:573-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 07 2018 18:53:373-CriticalT05.0SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 07 2018 18:13:383-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;
Apr 07 2018 18:13:253-CriticalR04.0Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=14:5b:d1:fa:c2:06;CMTS-MAC=00:01:5c:8a:b6:71;CM-QOS=1.1;CM-VER=3.0;

 

8 REPLIES
Spectator

Re: Internet cutting out multiple times a day

I looked and my downstream power level was -11 dBmV. I had a splitter for the TV and the Modem but I don't have TV service any more so I removed the splitter and now the power level is -4 dBmV. Hopefully this fixes the issue.
Helper

Re: Internet cutting out multiple times a day

Yes all those T3 timeouts are usually upload issues. While downstream -11 is low, it would be interesting to see what the upstream levels look like.

 

Can you post your current signal levels page?

Spectrum Employee

Re: Internet cutting out multiple times a day

@reds91185  here's what you were curious about from the HFC MAC:


Tx/Return/Upstream dBmV levels:

18.5  MHz @ 46

23.3 MHz @ 46.5

30.6 MHz @ 47

37.0 MHz @ 47.3

Spoiler
1.3 dB tilt, shouldn't be less if from tap, this looks more like a splitter

 


Rx/Forward/Downstream dBmV levels:

609 MHz @ -5.6

585 MHz @ -5.3

567 MHz @ -4.9

561 MHz @ -4.8

Spoiler
-5 power levels at this will work ok just fine, but would be ideally better if they were higher because below -8 dBmV or -10 dBmV and there can start to be issues if there's ingress/noise under the QAM carriers.  Contrary to popular opinion these can be at +15 dBmV with absolutely NO ISSUE (in tech ops even see call center CSRs get that wrong all the time...), DOCSIS 3.0 modems are designed for -15 to +15 dBmV, but of course -15 fails in real-world because SNR is too low.  So if you have to have imbalance, would prefer '+' over '-' on Rx power anyday.  (FYI:  0 dBmV is a reference power at exactly one millivolt voltage)

 

Experience-based conclusions from this data:

Would be worth it to know what the tap's levels and tilt are.  To me it looks like he still has a splitter somewhere, judging by the cable math.  Whatever the case regarding additional splitters between tap & modem, he can't use another splitter without  going above 50 dBmV Tx on this "outlet".  So removing the splitter was the correct solution.  Good job @tryglicer !


One question and one comment for you @tryglicer

 

1,  Is this a customer owned SB6121?  You're trying to shove 60x6 billing provisioning limits onto it (meaning a cap of 73.73Mbps down by 6.14Mbps up) onto a 4x4 modem (4 upstream channels/frequencies, 4 downstream).  While that WILL work on a DOCSIS 3.0 modem with those speeds, it's be better for you in the long run to upgrade to a 16x4 like the SB6183 (if you want to stay in the same modem model series).  Plus that way you benefit branch out on 16 different channels to distrubute how much bitrate load each would carry (in Mbps) from the server (CMTS).  Your plant in the area you live in at least a 16 channel downstream capable (but 32 channel is probably wasted potential at this time, so don't waste your money).

 

2. You STILL seem have a splitter, either that or your tap is jacked up (which is far less likely).  I'd recommend getting a unity-gain (aka. no-loss, no-gain) amp installed.  Just need to schedule that with us and we can can come out an see if that can be done (should be able to, even on MDUs)  We can check the tap, check fittings, and install an amp instead of a splitter (just would need somewhere to power it from, or power-insert from).

 

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

Re: Internet cutting out multiple times a day

They were all at 52 before I removed the splitter this is what its at now 

Downstream Bonding Channel Value
Channel ID10 11 14 18 
Frequency561000000 Hz 567000000 Hz 585000000 Hz 609000000 Hz 
Signal to Noise Ratio37 dB 37 dB 37 dB 37 dB 
Downstream ModulationQAM256 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  -5 dBmV  -5 dBmV  -5 dBmV  

 

Upstream Bonding Channel Value
Channel ID57 60 59 58 
Frequency18500000 Hz 37000000 Hz 30600000 Hz 23300000 Hz 
Ranging Service ID10880 10880 10880 10880 
Symbol Rate2.560 Msym/sec 5.120 Msym/sec 5.120 Msym/sec 5.120 Msym/sec 
Power Level46 dBmV 47 dBmV 47 dBmV 47 dBmV 
Upstream Modulation[3] QPSK
[2] 16QAM
 
[3] QPSK
[1] 16QAM
[2] 64QAM
 
[3] QPSK
[1] 16QAM
[2] 64QAM
 
[3] QPSK
[1] 16QAM
[2] 64QAM
 
Ranging StatusSuccess Success Success Success 

 

Signal Stats (Codewords) Bonding Channel Value
Channel ID10 11 14 18 
Total Unerrored Codewords339317719 339317720 339317734 339317744 
Total Correctable Codewords61 107 54 41 
Total Uncorrectable Codewords652 604 648 652 
Helper

Re: Internet cutting out multiple times a day

Agreed...the 6121 is obsolete and really should be replaced. Also agreed that you likely have another splitter somewhere. Do you have a splitter where the main line comes into your house? If so, that one could probably be replaced with a ground block barrel or the amp @agentx5 mentioned.

Contributor

Re: Internet cutting out multiple times a day

If you have US power levels of 47-48 dBm now, then with that splitter installed you would have had US power levels well into the 50's.  That's up against the limit and seeing T3 timeouts under those conditions is not surprising.    Should be better now.  The SB6121 is getting close to being obsolete but if it is working for you then you should be good. 

Proven Sharer

Re: Internet cutting out multiple times a day

One factor working AGAINST your Arris or Motorola SB6121 is its narrow receiver bandwidth (only 6 channels-36 MHz), because Spectrum's CMTS is now assigning a much wider block of DS channels for your data downloads. 

When you start shopping for a newer cable data modem, look for the key words "full range receiver" and either 16 or 24 channels.  You need both to get the best performance from your cable internet connection now and for several years in the future.  

Spectrum Employee

Re: Internet cutting out multiple times a day

Good Morning,

 

I will certainly Echo the responses for a new modem, while at your service speed a new modem may not give you any higher speeds, it does give your modem a much better spread of channels as to get your data from and shares load balancing.

 

Just like traffic flows better over 4 lanes as opposed to 2, Data flows better of 16 channels as opposed to 4.

 

The bigger brother which works fantastically, would be the SB6183, same model line, just a newer generation with better hardware in it, that allows for spectrum to provide speeds of up to 350Mbps without another new device anytime soon. While this is only one solution, there are many issues now with the 4channel modems that this can help resolve.

 

Aside from that, one of the other major considerations with your service is the hardware. -5 for an internet only connection is still a bit low, and my personal approach with this would be looking for more splitters, either at your tap connection, or at the outside box attached to your house/apartment. These all need to be removed.

 

Realistic signal target should be 0, -5 is good, but it makes me think with T3 errors and timeouts, is there something defective that needs to be pulled out. I would be looking for those bad splitters or connectors to replace them as well and see about getting that signal up even more. My personal target is +/- 3Dbmv in the field, though some devices can work as far out as +/- 15Dbmv, so 5 is well within the accepted range.

 

So aside from signal, the quality of it is important as well, and with all 4 channels having some level of uncorrected codeword errors makes me think you have something else causing issues that will need to be found and repaired before your issues will be resolved.

I post on my off hours, away from work and any statements made are my opinions, and do not necessarily reflect the views and beliefs of Spectrum Communications.