Multiple Flats-Same issue in big estate for months. SYNC Timing Synchronization failure - Loss of Sync

[paulk134]

Good afternoon,

I'm writing regarding the estate community that uses VM Broadband as the main ISP for 200+ flats under the same “cable”. 

In the last 3 months we started to experience severe internet dropdowns/reconnects that according to network logs from 192.168.0.1 hub settings looks like: “SYNC Timing Synchronization failure - Loss of Sync;CM-MAC= ******;CMTS-MAC=*****;CM-QOS=1.1;CM-VER=3.0;

In these 3months the issue was reported by multiple people in the estate and engineers visited multiple times, also there were “engineers working in your area” reports from virgin service status website. While after “engineer works” connection stabilised for time being, issues kept coming back after a week. 

In this post I’ll try to provide as much details as possible to help engineers to fix this, as well I asked all the estate to provide necessary data from their side, as this situation is affecting a lot of peoples jobs. 

1. One of the engineers suggested during the visit to reset the router - we all did that. Issue not fixed. 
2. I found out in a forum that it could be cable not tight enough on flat level and street cabinet level. I tighten up mine with a wrench. Can’t get to the street cabinet to make the same there. Issue not fixed.

Network Log

Time	Priority	Description
08/08/2022 13:19:59	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 13:19:16	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 13:19:11	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 13:19:11	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 13:19:11	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 13:18:28	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 13:18:18	notice	LAN login Success;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

Also I have set up a broadband quality monitor:

broadband quality monitor

Working from home in this conditions for 2-3months now is impossible.

Please Help

[paulk134]

In our estate, people are going to work in coffee places with wifi and creating hotspots from mobile phones to get work done, this is insane virgin media...

[jbrennand]

Can you do this
______________

In your browser’s URL box type in http://192.168.0.1 (or http://192.168.100.1 - if in modem mode) (DONT click these links) - and hit return. On the first page up dont login (unless you have the Hub4/5 - when you do have to login) just click on the “router status” icon/text at bottom-middle (Hub3/4) or top/right (SH’s) of the Login page.

Then Navigate to these “pages” and just copy/paste the normal “Formatted Text” (not images) 3 FULL sets of data onto here – 2 tables 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. If character limits are “exceeded” - just do two posts

[paulk134]

Hi John,

thanks for taking time, here are the tables.

Downstream bonded channels

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

1	234750000	-5.2	38	256 qam	13
2	138750000	-2.5	38	256 qam	1
3	146750000	-2.9	38	256 qam	2
4	154750000	-2.7	38	256 qam	3
5	162750000	-2.5	38	256 qam	4
6	170750000	-2.5	38	256 qam	5
7	178750000	-2.7	38	256 qam	6
8	186750000	-2.7	38	256 qam	7
9	194750000	-3	38	256 qam	8
10	202750000	-3.7	38	256 qam	9
11	210750000	-4.7	38	256 qam	10
12	218750000	-5.4	37	256 qam	11
13	226750000	-5.5	37	256 qam	12
14	242750000	-4.7	38	256 qam	14
15	250750000	-4.4	38	256 qam	15
16	258750000	-4.2	38	256 qam	16
17	266750000	-4	38	256 qam	17
18	274750000	-4	38	256 qam	18
19	282750000	-3.9	38	256 qam	19
20	290750000	-4.2	38	256 qam	20
21	298750000	-3.9	38	256 qam	21
22	306750000	-3.5	38	256 qam	22
23	314750000	-3.4	38	256 qam	23
24	322750000	-3.5	38	256 qam	24

Downstream bonded channels

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

1	Locked	38.6	143806	624598
2	Locked	38.6	154315	212564
3	Locked	38.6	128204	203273
4	Locked	38.6	119944	157202
5	Locked	38.9	116087	126264
6	Locked	38.6	112786	133604
7	Locked	38.9	108119	132078
8	Locked	38.6	101262	154724
9	Locked	38.6	96262	179866
10	Locked	38.9	100715	231911
11	Locked	38.6	136253	374035
12	Locked	37.6	129557	693754
13	Locked	37.6	126262	697450
14	Locked	38.6	166607	493745
15	Locked	38.6	162597	418096
16	Locked	38.9	149289	365360
17	Locked	38.9	122296	260231
18	Locked	38.9	105436	288607
19	Locked	38.9	105770	325545
20	Locked	38.6	104447	352503
21	Locked	38.6	101439	327485
22	Locked	38.6	104233	229141
23	Locked	38.9	103076	223924
24	Locked	38.9	106701	218349

Upstream bonded channels

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

1	49599984	30.5	5120	32 qam	6
2	30100000	33.5	5120	32 qam	9
3	43099939	33	5120	32 qam	7
4	36600000	34	5120	32 qam	8
5	23599693	33.2	5120	32 qam	10

Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1	ATDMA	0	0	2	0
2	ATDMA	0	0	4	0
3	ATDMA	0	0	1	0
4	ATDMA	0	0	1	0
5	ATDMA	0	0	0	0

[paulk134]

AND here are Network logs:

Network Log

Time	Priority	Description
08/08/2022 14:14:32	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:14:32	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:14:14	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:14:14	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:14:1	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:14:1	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:12:51	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:12:38	notice	LAN login Success;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:08:51	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:08:51	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:06:49	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:06:49	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:06:15	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:06:15	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:06:11	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:06:11	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:06:9	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:06:9	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:03:22	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2022 14:03:22	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

[jbrennand]

Dreadful

5 up channels is not usual - and their power levels are all low and the qam's should be 64 and lots of errors - can you do this
________________________

Do a Hub “pinhole reset” - first make sure the 2 passwords on the Hub sticker are still there and legible first ! Disconnect any ethernet cables from the Hub (leave the coax connected), and then with the Hub still "switched on" throughout, press pin in firmly with paper clip/SIM tray tool or similar "thin thing" and hold it firmly for at least 60 (a timed sixty) seconds, release the pin, leave for 5’ to stabilise - dont manually switch it off at any time. Passwords and SSID’s will reset to those on the sticker.

See if that restores 4 Up channels at 64 QAM.

[paulk134]

Hi John,

just did EXACTLY as you said (with exact timer for 60sec on phone).

managed to swap one channel from 32qam to 16qam 😄

let me know what tables should I post right now. 

[jbrennand]

Try this it should reset everything to 0
________________________________

Switch the Hub off and unplug it from the mains supply for five minutes. Whilst it's off, do a quick check that all of your coax and ethernet 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. Also check that the internal wiring is ok with no kinking or chaffing, check that all looks good with the outside cabling and wall box (no “staples, etc.,) piercing the cables. Then switch the Hub back on and leave ~5 minutes

When all done, check back in the settings and ensure that the RS error counts and T3 errors 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 and T3 ones) you have a problem (noise) that only a Tech visit will sort.

[ProofPlains]

Thanks for posting this Paul.

I'm one of your neighbours and have been experiencing the same as you for months now. 

[paulk134]

Hi John,

did all the things you have listed, tighten up all cord ends, used brand new ethernet cable, all looks tight and clean. No loose cords.

Yesterday also spoke with virgin tech person, he got all my notes on the issue, at the end of the day I received text from virgin that the issue has beed solved and I need to reset VM Hub and wait 30min. 

after 24h of observation, here are the results.

• dissconection keeps on going, had Google Duo call with my mum, every 5-10min I saw notification: "we using data because WiFi signal is poor"
• also watched youtube video, audio and video was jittery/laggy was imposible to understand what person speaks (480p resolution)
• simple google search websites when trying to reload on connection loss, takes realy too long
• etc. could continue the list

Please find attached thinkbroadband screenshot (the red line is when 30min reset/restart took place). Although in chart looks like there was 10 ping spikes, on connected devices felt WAY more..

Also will copy/paste same logs that you asked yesterday.

Greatly appreciate your help.