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neilp2
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"SYNC Timing Synchronization failure" SH3 intermittent drop outs

Hi all, my 350Mbps VM is often impressive (hitting over 300Mbps even now on a saturday evening) but other times terrible and dropping out the connection for up to a minute or two which drops zoom/teams/video streaming etc. 

The network log includes messages like:

critical

SYNC Timing Synchronization failure - Loss of Sync;

Warning!

RCS Partial Service;

 


It impacts all devices, wired or wireless.  Yesterday morning was terrible, many many drop outs during a two hour period with upload dropping below 0.1Mbps when connected.  I rebooted everything, tested with different devices, same issue. Used the VM check status pages etc which all said ok. 
I called VM support, ran some tests but said nothing was wrong with the router and I should just factory reset the router, which I didn't do as it would reset all the passwords, and some hours later it was working fine again. The believed it was just wifi contention issues which I don't believe as most of the time it's ok...

I've started logging with thinkbroadband which is showing large periods of packet loss. Also looking at the router Network log and seeing many critical and Warning notices -- see below.

This is the last 24 hours:

neilp2_0-1618695971919.png

 

https://www.thinkbroadband.com/broadband/monitoring/quality/share/8256fbc257c5c64c821651521af2643df0...


This is the most recent Hub router status Network Log:

Time

Priority

Description

17/04/2021 20:27:37

notice

LAN login Success;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 15:10:55

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 15:09:45

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 15:03:17

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 15:03:1

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 14:57:35

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 14:57:11

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 14:53:47

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 14:53:45

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 14:51:13

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 14:51:13

critical

No Ranging Response received - T3 time-out;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 10:48:35

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 10:48:6

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 10:40:32

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 09:26:34

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 08:29:51

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 08:29:25

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 07:46:37

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 05:55:27

critical

No Ranging Response received - T3 time-out;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

17/04/2021 05:26:10

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

 

Here's some speedtest.net results, you can see how bad it was yesterday morning (16th, 9-10am) even while on the phone to VM support!

neilp2_1-1618696000740.png

 

[I'll post the rest of the router logs seperately as the forum complains of a 20,000 character limit]

Any advice on how to resolve? Should I just keep calling VM support until I find someone that can help?

Many thanks!

Neil.

 

 

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neilp2
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Re: "SYNC Timing Synchronization failure" SH3 intermittent drop outs

Here are the other Router Status pages -- note the router was rebooted 36 hours ago (April 16th, between 9 & 10 am)

neilp2_0-1618695103062.png

 

Downstream bonded channels

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

1139000000240256 qam1
2147000000240256 qam2
3155000000238256 qam3
41630000001.740256 qam4
51710000001.540256 qam5
61790000001.240256 qam6
71870000001.440256 qam7
81950000001.240256 qam8
9203000000140256 qam9
102110000000.740256 qam10
112190000000.940256 qam11
122270000000.740256 qam12
132350000000.540256 qam13
14243000000-0.240256 qam14
15251000000-0.240256 qam15
16259000000040256 qam16
17267000000040256 qam17
182750000000.440256 qam18
192830000000.240256 qam19
202910000000.440256 qam20
212990000000.940256 qam21
223070000000.740256 qam22
23315000000140256 qam23
243230000000.740256 qam24



Downstream bonded channels

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

1Locked40.343873772631520
2Locked40.32251365866991
3Locked38.943758562555726
4Locked40.350600593870622
5Locked40.32473604810761
6Locked40.341262133738038
7Locked40.324828942266594
8Locked40.379992547658
9Locked40.330045912357
10Locked40.9549522321
11Locked40.3918481589
12Locked40.335238268852
13Locked40.334078140242
14Locked40.3775254919
15Locked40.9209742775
16Locked40.315402211985
17Locked40.382333156456
18Locked40.338986313043
19Locked40.318214351931
20Locked40.32650414358
21Locked40.350841827126
22Locked40.312984411824
23Locked40.32575117
24Locked40.355431

177

 

Upstream bonded channels

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

13940007345.8512064 qam8
24620000046.8512064 qam7
36029999447.3512064 qam5
45369999346.5512064 qam6



Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0030
2ATDMA0040
3ATDMA0000
4ATDMA0040

 

General Configuration

Network access
Allowed
Maximum Number of CPEs
1
Baseline Privacy
Enabled
DOCSIS Mode
Docsis30
Config file
cmreg-vmdg505-bbt062-b.cm



Primary Downstream Service Flow

SFID6820
Max Traffic Rate402500089
Max Traffic Burst42600
Min Traffic Rate0



Primary Upstream Service Flow

SFID6819
Max Traffic Rate38500089
Max Traffic Burst42600
Min Traffic Rate0
Max Concatenated Burst42600
Scheduling TypeBestEffort

 

 

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neilp2
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Re: "SYNC Timing Synchronization failure" SH3 intermittent drop outs

... also adding additional network log from yesterday - (Friday 16th morning) which includes the worst drop which started around 8:30 and continued will after 10am. This includes the time while I was on the phone to Virgin Media support who said the router was OK:

Time

Priority

Description

16/04/2021 09:36:22

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:36:19

critical

No Ranging Response received - T3 time-out;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:34:47

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:34:44

notice

LAN login Success;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:34:0

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:33:48

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:31:38

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:31:37

critical

No Ranging Response received - T3 time-out;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:30:26

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:29:5

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:28:18

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:27:25

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:24:31

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:23:7

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:18:48

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:18:45

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:16:53

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:15:57

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:15:25

Warning!

RCS Partial Service;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

16/04/2021 09:15:9

critical

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=*CMTS-MAC=*CM-QOS=1.1;CM-VER=3.0;

 

Started logging shortly after:

neilp2_0-1618695684654.png

https://www.thinkbroadband.com/broadband/monitoring/quality/share/423d7818553ab7e992d544d21619320268...

 

Many thanks for anyone that can help  🙂

Neil.

 

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Beth_G
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Re: "SYNC Timing Synchronization failure" SH3 intermittent drop outs

Hey neilp2,

 

Thanks for posting on the Community Forums, sorry to see you're suffering from a few broadband issues.

 

I'm going to book you in with an engineer visit for this one as I can see there's a lot of errors logged.  I've booked in the next available slot for you, you'll just need to head over to your My Virgin Media account to view the appointment time slot.

 

Let me know how the visit goes and if there's anything else you need!

 

Kind regards,

 

Beth

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neilp2
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Re: "SYNC Timing Synchronization failure" SH3 intermittent drop outs

Hi Beth - thanks for setting up an engineer visit for the next day.  Unfortunately the timing wasn't convienient and I've searched all over the My Virgin Media pages but cannot see how to change the appointment.

Please could you setup a new appointment on Monday 26th April?

Many thanks,

Neil

 

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Beth_G
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Re: "SYNC Timing Synchronization failure" SH3 intermittent drop outs

Hi Neil, 

 

Sorry to hear the time wasn't convenient and you struggled to find where to rearrange your appointment. Were you accessing My Virgin Media via the webpage or the app?

 

I've just gone back onto your account to change the appointment, and it looks like there's now an identified outage in the area - it looks like we're doing some maintenance work which is due to be fixed by 3pm today. Can you please let me know how you get on after this time and if you are still experiencing issues, I can book in another appointment for you?

 

Kind regards,

 

Beth 

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neilp2
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Re: "SYNC Timing Synchronization failure" SH3 intermittent drop outs

Hi Beth,

I was using the web page (I've not installed the app).

It would be great if you can book an appointment for Monday please.  I can cancel nearer the time if the regional maintenance fixes the issue.

Thanks for your help,

Neil.

 

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Beth_G
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Re: "SYNC Timing Synchronization failure" SH3 intermittent drop outs

Hi Neil,

 

How are things now? I can try and book in the appointment for you, however as there is a known area issue it's likely that the appointment will automatically get cancelled until the outage has cleared. I am happy to try and book it again for you now if you are still struggling with the connection.

 

Kind regards,

 

Beth

 

 

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