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OX2
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Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per hour

As of yesterday, my Virgin connection (in the OX2 area) is completely unreliable. Ping times to the local VM core router (oxfd-core-2a-xe-033-0.network.virginmedia.net) jump up to >100000 msec (that's >100 seconds!) multiple times an hour. Every video call gets interrupted. That's on a wired connection (this is not a WiFi issue).

I'm on a Hub 3.0; when I check the router status through its web interface it shows "Timing Synchronization failure - Loss of Sync" critical errors whenever the connection breaks (see screenshots). I've tried powercycling it, but to no avail.

This has been happening on and off for months now: the connection is a affected for a few days, then it's back to normal for a week or two. Then a few weeks later it's bad again for a few days, etc etc. On Twitter, a customer service representative suggested I ask here. Other similar posts suggest that an engineer would need to visit. Weirdly, a colleague who lives one street over from me and is also on VM doesn't have any problems.

 

 

Ping stats:

ping.png

 

"Downstream" tab on "Router status" shows a lot of "Pre RS Errors" and "Post RS Errors" on all channels:

router-status-downstream.png

"Network log" tab shows repeated "Warning!" and "critical" errors, citing "RCS Partial Service" and "Timing Synchronization failure" and "Loss of sync" (I've removed the MAC addresses in case that's a problem):

router-status-network-log-nomac.png

In case it's relevant, this is the router configuration tab:

router-status-configuration.png 

Let me know if you need any more debugging information.

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jbrennand
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Message 2 of 31
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Re: Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per h

The RS errors may be an issue - reset them and then post up all of the data as per the protocol below
________________________________________________

Switch the Hub off and unplug it for a few minutes and then start up. Whilst it's off, do a quick check that all of your coax cable connections are in nice and "finger" tight - at the Hub and wall box and also at any connectors etc. Ensure there are no “unterminated cable loose ends. Disconnect all the connections and reconnect to be sure.

When done, check back in the settings and ensure that the RS error counts have all reset to 0. Then check every hour or so to see if they start reappearing - they shouldn't. If they do (particularly the postRS ones) you have a problem (noise) that only a Tech visit will sort.
-------------------------
Copy/paste as “Formatted Text” (not images) 3 FULL sets of data onto here – 2 pages from the Downstream, 2 from the Upstream, & the Network Logs page. Don't worry too much about the formatting it can be easily read & DON’T include personal data or MAC addresses - blank them out - if you copy/paste the data, the board software will do this for you (you may need to click the "submit" button again.
_________________________________________
Also, in the meantime... If you haven’t already, set up a free, secure and “offlsite” - “Broadband Quality Monitor” to continually monitor the state of your connection and record any true network dropouts , latency issues, packet drops, etc - it will thus allow you to differentiate between those and simple wifi dropouts. It does it 24/7/365 and it keeps a visual record of any/all of your network disconnections, useful data to have to match to the Network logs (in your Hub settings) and also in discussions with VM - note it will take a few hours to start seeing a sensible picture - post up the “link” to the “share live graph” (as per instructions on the TB website) when it starts to develop.

https://www.thinkbroadband.com/broadband/monitoring/quality

--------------------
John
--------------------

I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.
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OX2
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Message 3 of 31
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Re: Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per h

Thanks @jbrennand! I've switched the modem off, checked all the connections, turned it back on. All Pre RS and Post RS errors indeed reset to 0, but Pre RS errors are already coming in. I'll keep an eye on it in the coming hours and if there are more Post RS errors I'll add another post to this thread with the data.

In the meantime, here's a live graph by thinkbroadband.com:

12db9f92d28c015d49f285c2e3c381d24ca89622



Downstream (as of 2.05pm BST, after reset)

Downstream bonded channels
Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID
1 498250000 -4 40 256 qam 12
2 490250000 -4.5 38 256 qam 11
3 506250000 -4 40 256 qam 13
4 514250000 -4.2 40 256 qam 14
5 522250000 -3.9 40 256 qam 15
6 530250000 -4.7 38 256 qam 16
7 538250000 -4.4 38 256 qam 17
8 546250000 -4.4 38 256 qam 18
9 554250000 -5.2 38 256 qam 19
10 562250000 -4.4 38 256 qam 20
11 570250000 -4.5 38 256 qam 21
12 578250000 -5 40 256 qam 22
13 586250000 -4.7 40 256 qam 23
14 594250000 -6 38 256 qam 24
15 658250000 -6.7 38 256 qam 25
16 666250000 -6.4 38 256 qam 26
17 674250000 -5.5 38 256 qam 27
18 682250000 -6.2 38 256 qam 28
19 690250000 -6 38 256 qam 29
20 698250000 -7.2 38 256 qam 30
21 706250000 -7.5 38 256 qam 31
22 714250000 -6.7 38 256 qam 32
23 722250000 -7 38 256 qam 33
24 730250000 -7.2 38 256 qam 34


Downstream bonded channels
Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors
1 Locked 40.3 1426 0
2 Locked 40.3 3162 0
3 Locked 38.9 1838 0
4 Locked 40.3 1384 0
5 Locked 40.3 1289 0
6 Locked 40.3 1274 0
7 Locked 38.6 1286 0
8 Locked 38.9 1165 0
9 Locked 38.9 992 0
10 Locked 38.9 839 0
11 Locked 38.9 821 0
12 Locked 38.9 714 0
13 Locked 40.3 673 0
14 Locked 40.9 623 0
15 Locked 38.9 620 0
16 Locked 38.6 380 0
17 Locked 38.6 373 0
18 Locked 38.6 353 0
19 Locked 38.6 324 0
20 Locked 38.9 318 0
21 Locked 38.6 320 0
22 Locked 38.9 305 0
23 Locked 38.9 299 0
24 Locked 38.6 285 0

Upstream (as of 2.05pm BST, after reset)
Upstream bonded channels
Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID
1 39400000 36.3 5120 64 qam 6
2 46200000 36.5 5120 64 qam 5
3 32600000 36 5120 64 qam 7
4 25800000 35.5 5120 64 qam 8


Upstream bonded channels
Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts
1 ATDMA 0 0 0 0
2 ATDMA 0 0 0 0
3 ATDMA 0 0 0 0
4 ATDMA 0 0 0 0

Network logs
(no additional data since rebooting)

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jbrennand
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Message 4 of 31
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Re: Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per h

Ahhh... now I see... all of your Down power levels are too low. -6dBmV is the recommended minimum level many are below that. That is probably causing the issues.

Lets see the BQM link too

You will need a tech visit to get them back into range. Try calling it in first and a VM person should pick this up here ina a day or so

--------------------
John
--------------------

I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.
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Message 5 of 31
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Re: Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per h

Thanks for your help! What do you mean by "Try calling it in first"? Phone them up? Tried that before, but that just resulted in someone telling me to turn it off and on again.

I've updated my response above to have the link, but the image needs reviewing. Here's the URL: https://www.thinkbroadband.com/broadband/monitoring/quality/share/12db9f92d28c015d49f285c2e3c381d24c...
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Message 6 of 31
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Re: Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per h

As expected, it's continuing to happen. Here's the data from the downstream and upstream tabs (network logs to follow — exceeds 20k characters):

 

Downstream

Downstream bonded channels

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

1498250000-440256 qam12
2490250000-4.538256 qam11
3506250000-4.240256 qam13
4514250000-4.240256 qam14
5522250000-440256 qam15
6530250000-4.738256 qam16
7538250000-4.238256 qam17
8546250000-4.238256 qam18
9554250000-5.238256 qam19
10562250000-4.239256 qam20
11570250000-4.438256 qam21
12578250000-540256 qam22
13586250000-4.740256 qam23
14594250000-638256 qam24
15658250000-6.738256 qam25
16666250000-6.438256 qam26
17674250000-5.538256 qam27
18682250000-638256 qam28
19690250000-638256 qam29
20698250000-7.238256 qam30
21706250000-7.538256 qam31
22714250000-6.738256 qam32
23722250000-7.238256 qam33
24730250000-7.238256 qam34



Downstream bonded channels

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

1Locked40.31429475380
2Locked38.916435911458
3Locked40.31265636984
4Locked40.31180199239
5Locked40.31191187268
6Locked38.91184548789
7Locked38.91024538617
8Locked38.9911747710
9Locked38.9812138149
10Locked39.3738857639
11Locked38.6683789821
12Locked40.3627107100
13Locked40.3599699677
14Locked38.9566267225
15Locked38.9369467511
16Locked38.6343808115
17Locked38.9319488227
18Locked38.63093211938
19Locked38.9301879156
20Locked38.6304678360
21Locked38.6300919962
22Locked38.6283989357
23Locked38.9268209326
24Locked38.9262079256

 

Upstream

Upstream bonded channels

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

13940000036.3512064 qam6
24620000036.5512064 qam5
33260007436512064 qam7
42580000035.5512064 qam8


Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0000
2ATDMA0000
3ATDMA0000
4ATDMA0000

 

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Message 7 of 31
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Re: Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per h

Network log (new entries since reboot, I think timestamps are UTC rather than BST)

Network Log

Time Priority Description

27/07/2021 13:54:47Warning!RCS Partial Service;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;
27/07/2021 13:54:47criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;
27/07/2021 13:31:50Warning!RCS Partial Service;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;
27/07/2021 13:31:50criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;
27/07/2021 13:30:44Warning!RCS Partial Service;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;
27/07/2021 13:30:44criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;
27/07/2021 13:30:24Warning!RCS Partial Service;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;
27/07/2021 13:30:24criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;
27/07/2021 13:21:16Warning!RCS Partial Service;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;
27/07/2021 13:21:16criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=XXX;CMTS-MAC=XXX;CM-QOS=1.1;CM-VER=3.0;

 

Here's the live thinkbroadband.com graph.

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Message 8 of 31
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Re: Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per h

You have a dreadful connection.

I will flag for VM to come here to look at it - keep checking back

--------------------
John
--------------------

I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.
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Message 9 of 31
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Re: Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per h

Hello @OX2.

 

Welcome to the community page, thank you for posting on here.

 

I am sorry for the issue you are having so far.

 

I was unable to locate your account using your forums details, please can you tell me if you have called to report this previously and if so what advice was given?

 

Look forward to your response.

Hayley
Forum Team



New around here? To find out more about the Community check out our Getting Started guide


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Message 10 of 31
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Re: Unreliable connection: "Timing Synchronization failure - Loss of Sync" multiple times per h

I reported this multiple times on Twitter, and spoke to customer support I think last year when it first started to happen. The advice I got was to reset the modem, which never actually helped. But because the problems are intermittent (they typically go away after a couple of days, only to come back after a few weeks) I've never actually had the opportunity to dig deeper. This time it seems even worse than before.

My Virgin Media account number is XXXX. Based on @jbrennand assessment, it sounds like we need an engineer on-site to resolve this problem.

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