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Intermittent SYNC Timing Synchronization failure

nickbracko
Tuning in

Hello,

I've recently moved into a new house with an existing Virgin fibre (M100) connection I've taken over, and after plugging the new router in I'm getting dropouts most days for a few minutes between 2pm and 4pm, that look like they're due to a loss of signal. This has been happening for about 3 weeks now.

I've searched the forums, and it seems like everyone else who experiences the same problem typically end up needing either a new router or an engineer visit to look at the line. 

Normally we get good speeds - 70mbs or so - but then for a few minutes most afternoons there's this really annoying intermittent drop out. Always between 2 and 4pm . 

When I look at the error log, this is the typical mix (and duration) of messages:

31/07/2020 14:48:46criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
31/07/2020 14:48:38criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
31/07/2020 14:48:36Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
31/07/2020 14:48:18criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
31/07/2020 14:47:50criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
31/07/2020 14:47:39Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
31/07/2020 14:47:9criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
31/07/2020 14:46:36Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

 

Downstream looks like this:

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

1139000000340256 qam1
21470000002.540256 qam2
31550000002.940256 qam3
4163000000340256 qam4
51710000003.240256 qam5
6179000000340256 qam6
71870000003.240256 qam7
81950000003.540256 qam8
92030000003.540256 qam9
102110000003.740256 qam10
112190000003.440256 qam11
122270000003.740256 qam12
13235000000340256 qam13
142430000003.240256 qam14
152510000003.240256 qam15
162590000003.540256 qam16
172670000003.540256 qam17
182750000003.540256 qam18
19283000000440256 qam19
202910000003.740256 qam20
212990000004.340256 qam21
223070000003.940256 qam22
233150000004.540256 qam23
24323000000440256 qam24

 

Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors

1Locked40.38354955554
2Locked40.37775862717
3Locked40.31235161122677
4Locked40.31653801619354
5Locked40.910909351440
6Locked40.91716846464880
7Locked40.3103601651659
8Locked40.34798925919
9Locked40.94500325595
10Locked40.97611927281
11Locked40.97035226109
12Locked40.34145021016
13Locked40.35860322829
14Locked40.98755822351
15Locked40.33867819833
16Locked40.33859519192
17Locked40.35790521477
18Locked40.33956917482
19Locked40.32803815182
20Locked40.92813415223
21Locked40.34144215372
22Locked40.93228014074
23Locked40.32529613643
24Locked40.32802013905

 

And upstream like this:

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

1603001125.4512064 qam1
2537001135.4512064 qam2

 

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0000
2ATDMA0000

 

 

15 REPLIES 15

Hi Paul,

Excuse my delayed response - I missed the notification of your reply. I've swapped the Hub back into router mode (I have a Deco M4 mesh network that I usually use across the house). 

The last 48 hours have been particularly bad - again it seems to correlate with hot weather, and the hottest period of the day. This afternoon I've been getting drops every few minutes to the point that the internet is unusable. See error log below.

Drop outs also seem to correlate when I'm using lots of upload capacity (i.e. on Zoom calls). Anecdotally, just before the web goes down for a couple of minutes the other members of Zoom calls I'm on stop seeing or hearing me, but for perhaps 30 seconds I continue receiving a perfectly clear video and audio feed from them (which had made for some entertaining situations...).

Given the prior problems with upload channels noted earlier in this thread, I wonder if something is wrong with the upstream sync?

DM me if easier to diagnose this over a call. I'll leave the Hub in router mode for you to look more closely at the problem.

Time Priority Description

16/09/2020 16:16:13criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:15:57criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:15:57Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:14:47noticeLAN login Success;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:14:11criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:14:10Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:14:10criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:13:1criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:11:36criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:11:35Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:01:34criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:04:41Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:04:41criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:01:47Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:00:48noticeLAN login Success;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 16:00:9criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 15:59:58Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 15:59:25criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 15:55:38Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2020 15:54:29criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

Hi VM Team,

Can I please get an update from someone on the VM team on how I can get an engineer out to sort this please? I just called the technical help line to try and sort this, and I think they just follow a checklist which involved "Try plugging in via a LAN cable", sending me a link to a "How to Improve my Wi-Fi speed" and "monitor it for 7 days and see if anything changes". I'm not sure any of the error messages we discuss here meant anything to them 😭

I'm still losing connection pretty consistently several times per day, to the point that if I have important client video calls I'm travelling 1h30m to the office just to take the call to make sure it doesn't drop part way through.

What is the best way to get this sorted, as it seems everyone on this forum really understands the tech vs the telephone support who really don't.

Thank you as ever for your support. I'll save posting another set of logs from the router, as they're all pretty consistent with the previous ones I've posted, but can add them in here if helpful again!

Nick

Hi @nickbracko,

 

Sorry to hear that you're still having problems with your connection despite replacing the cabling. I've had a look at your network details and can confirm that the power level ranges are all fine. There are also no issues with utilisation or SNR. However you do have high numbers of T3 since your last Hub reboot 3 days ago. Given the ongoing issues, I've arranged for an engineer visit to take a look at it and you can find the details of it via your online account where you can re-arrange it if necessary.

 

Please keep us updated.

 

Thanks,

 

Lisa

Brill - thanks so much Lisa! Really appreciated.

Hi, did this get resolved and if so what was the solution please?  I am having same issue.  Had a technician visit 2 weeks ago and replaced hub but couldn’t find a problem!  Not surprisingly the issue has re-occurred, so would be grateful to know what the solution is.  Thanks.

Thanks for your post @Scottpm

 

I can see that you've been able to speak to our team earlier in the week and an engineer has been booked for you

 

Do please drop us an update and hopefully we'll have some good news to read through

 

Kindest regards,

David_Bn