SYNC Timing Synchronization failure - Loss of Sync & RCS Partial Service

[NeedsCoffee]

My M125 connection has been really unreliable recently, with occassionally really bad latency, slow speeds and sometimes complete loss of service. I've got a Hub3 in modem mode and my systems are experiencing problems through ethernet not just wifi.

Log shows a few criticals and warnings: RCS Partial Service and also SYNC Timing Synchronization failure - Loss of Sync

Research of similar issues here suggests I need an engineer visit as it's likely to be something between my hub and the cab. I've done all the usual things, full power-off for 10 minutes and restart, as well as checking for tight cable connections. None of that has helped so far.

Could I get some help from a support tech please? Here are my logs.

Time	Priority	Description
01/10/2023 11:43:00	Warning!	RCS Partial Service; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
01/10/2023 11:43:00	critical	SYNC Timing Synchronization failure - Loss of Sync; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
01/10/2023 11:42:52	Warning!	RCS Partial Service; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
01/10/2023 11:42:08	critical	No Ranging Response received - T3 time-out; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
01/10/2023 11:40:16	critical	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
01/10/2023 11:38:07	critical	No Ranging Response received - T3 time-out; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
01/10/2023 11:38:07	critical	Unicast Ranging Received Abort Response - initializing MAC; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
01/10/2023 11:37:31	critical	No Ranging Response received - T3 time-out; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
01/10/2023 09:15:02	Warning!	RCS Partial Service; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
29/09/2023 19:27:41	critical	No Ranging Response received - T3 time-out; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
29/09/2023 11:33:22	Warning!	RCS Partial Service; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
29/09/2023 11:33:22	critical	SYNC Timing Synchronization failure - Loss of Sync; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
29/09/2023 05:29:57	Warning!	RCS Partial Service; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
28/09/2023 22:09:03	critical	No Ranging Response received - T3 time-out; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
28/09/2023 22:08:51	Warning!	RCS Partial Service; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
28/09/2023 16:59:52	critical	No Ranging Response received - T3 time-out; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
28/09/2023 09:36:29	notice	DHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt057-b.cm modified; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;
28/09/2023 09:36:29	Error	DHCP RENEW WARNING - Field invalid in response v4 option; CM-MAC=48:d3:43:xx:xx:xx; CMTS-MAC=28:52:61:xx:xx:xx; CM-QOS=1.1; CM-VER=3.0;

Thanks! Nick Clark.

[Tudor]

Please post a full set of stats, it looks like a circuit problem. 

[NeedsCoffee]

.

[NeedsCoffee]

Did you mean this stuff?

Downstream bonded channels

Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
1	387000000	-0.5	40	256 qam	32
2	251000000	1.4	38	256 qam	15
3	259000000	1.2	40	256 qam	16
4	267000000	1.2	38	256 qam	17
5	275000000	1	38	256 qam	18
6	283000000	0.7	38	256 qam	19
7	291000000	0.2	38	256 qam	20
8	299000000	0.4	38	256 qam	21
9	307000000	0	38	256 qam	22
10	315000000	-0.4	38	256 qam	23
11	323000000	-0.2	38	256 qam	24
12	331000000	-0.2	38	256 qam	25
13	339000000	0	38	256 qam	26
14	347000000	-0.2	38	256 qam	27
15	355000000	-0.4	38	256 qam	28
16	363000000	0	38	256 qam	29
17	371000000	0	40	256 qam	30
18	379000000	-0.4	38	256 qam	31
19	395000000	-0.7	40	256 qam	33
20	403000000	-0.9	38	256 qam	34
21	411000000	-0.9	38	256 qam	35
22	419000000	-1.4	38	256 qam	36
23	523000000	-5.2	37	256 qam	37
24	531000000	-5.7	37	256 qam	38

Downstream bonded channels

Channel	Locked Status	RxMER (dB)	Pre RS Errors	Post RS Errors
1	Locked	40.3	5	0
2	Locked	38.9	7	0
3	Locked	40.3	6	0
4	Locked	38.9	4	0
5	Locked	38.9	5	0
6	Locked	38.9	6	0
7	Locked	38.9	9	0
8	Locked	38.9	9	0
9	Locked	38.9	17	0
10	Locked	38.6	19	0
11	Locked	38.9	11	0
12	Locked	38.6	17	0
13	Locked	38.6	12	0
14	Locked	38.9	13	0
15	Locked	38.9	12	0
16	Locked	38.9	9	0
17	Locked	40.3	9	0
18	Locked	38.9	8	0
19	Locked	40.3	13	0
20	Locked	38.6	9	0
21	Locked	38.6	4	0
22	Locked	38.9	4	0
23	Locked	37.6	210	0
24	Locked	37.3	357	0

Upstream bonded channels

Channel	Frequency (Hz)	Power (dBmV)	Symbol Rate (ksps)	Modulation	Channel ID
1	23600000	43	5120	64 qam	5
2	30100000	43.5	5120	64 qam	4
3	36600000	43.5	5120	64 qam	3
4	43100000	43.5	5120	64 qam	2
5	49600000	45	5120	64 qam	1

Upstream bonded channels

Channel	Channel Type	T1 Timeouts	T2 Timeouts	T3 Timeouts	T4 Timeouts
1	ATDMA	0	0	2	0
2	ATDMA	0	0	1	0
3	ATDMA	0	0	0	0
4	ATDMA	0	0	0	0
5	ATDMA	0	0	0	0

[Carley_S]

Hi @NeedsCoffee 

Welcome to the community forums. 

Sorry to hear you're having issues with your service at this time. 

I have checked the systems at this side and all look good with your specs and I cannot find any issues within the area that might be causing this. 

I'm unable to run any further checks as your hub is in modem mode and we would need this in router mode to investigate anything else at our side. 

Are you able to place the hub into router mode and also set up and post a live broadband quality monitor on this forums and we'll support further with this issue. 

You can set up your live broadband quality monitor here. 

[NeedsCoffee]

Thanks for responding Carley. The live BQM is in my signature I'm pleased to say.

I will investigate switching to router mode tomorrow, however it would be a somewhat disruptive change and interfere with work so might not happen for a bit.
Here's an updated stats table in case it's useful, seem to be a lot of pre- and post- rs errors in the downstream.

Downstream bonded channels
Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
1	387000000	-0.9	38	256 qam	32
2	251000000	1.2	38	256 qam	15
3	259000000	1.2	40	256 qam	16
4	267000000	1	38	256 qam	17
5	275000000	0.7	38	256 qam	18
6	283000000	0.7	38	256 qam	19
7	291000000	0	38	256 qam	20
8	299000000	0.2	38	256 qam	21
9	307000000	-0.2	38	256 qam	22
10	315000000	-0.7	38	256 qam	23
11	323000000	-0.5	38	256 qam	24
12	331000000	-0.5	38	256 qam	25
13	339000000	-0.4	38	256 qam	26
14	347000000	-0.5	38	256 qam	27
15	355000000	-0.7	38	256 qam	28
16	363000000	-0.5	38	256 qam	29
17	371000000	-0.4	40	256 qam	30
18	379000000	-0.7	38	256 qam	31
19	395000000	-1	38	256 qam	33
20	403000000	-1	38	256 qam	34
21	411000000	-1.2	38	256 qam	35
22	419000000	-1.7	38	256 qam	36
23	523000000	-5.5	37	256 qam	37
24	531000000	-6	37	256 qam	38
Downstream bonded channels
Channel	Locked Status	RxMER (dB)	Pre RS Errors	Post RS Errors
1	Locked	38.9	352	486
2	Locked	38.9	485	425
3	Locked	40.3	494	2239
4	Locked	38.9	429	723
5	Locked	38.9	412	676
6	Locked	38.9	434	604
7	Locked	38.6	488	611
8	Locked	38.9	428	605
9	Locked	38.9	462	596
10	Locked	38.6	455	640
11	Locked	38.9	446	675
12	Locked	38.6	432	758
13	Locked	38.6	425	737
14	Locked	38.9	390	703
15	Locked	38.9	396	654
16	Locked	38.6	380	689
17	Locked	40.3	381	705
18	Locked	38.6	354	653
19	Locked	38.9	331	673
20	Locked	38.9	350	601
21	Locked	38.9	373	662
22	Locked	38.6	403	769
23	Locked	37.6	1640	778
24	Locked	37.6	2393	711
Upstream bonded channels
Channel	Frequency (Hz)	Power (dBmV)	Symbol Rate (ksps)	Modulation	Channel ID
1	23600000	43.5	5120	64 qam	5
2	30100000	45	5120	64 qam	4
3	36600000	45	5120	64 qam	3
4	43100000	45	5120	64 qam	2
5	49600000	45	5120	64 qam	1
Upstream bonded channels
Channel	Channel Type	T1 Timeouts	T2 Timeouts	T3 Timeouts	T4 Timeouts
1	ATDMA	0	0	2	0
2	ATDMA	0	0	0	0
3	ATDMA	0	0	0	0
4	ATDMA	0	0	0	0
5	ATDMA	0	0	0	0

Here are some monitoring graphs for the last few days...

Mon 2nd October
Mon 2nd Oct

 Tue 3rd October
Tue 3rd October

 Wed 4th October
Wed 4th October

 Thank you for your help!

[NeedsCoffee]

Thank you for replying Carley.
My live BQM is in my profile I'm pleased to say.

I'll investigate switching back to router mode tomorrow. It'll be a bit disruptive for my work so might be a while before I can do that.

Here are some up to date stats from the Hub3, getting loads of Rs errors in the downstream...

Downstream bonded channels
Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
1	387000000	-0.9	38	256 qam	32
2	251000000	1.2	38	256 qam	15
3	259000000	1.2	40	256 qam	16
4	267000000	1	38	256 qam	17
5	275000000	0.7	38	256 qam	18
6	283000000	0.7	38	256 qam	19
7	291000000	0	38	256 qam	20
8	299000000	0.2	38	256 qam	21
9	307000000	-0.2	38	256 qam	22
10	315000000	-0.7	38	256 qam	23
11	323000000	-0.5	38	256 qam	24
12	331000000	-0.5	38	256 qam	25
13	339000000	-0.4	38	256 qam	26
14	347000000	-0.5	38	256 qam	27
15	355000000	-0.7	38	256 qam	28
16	363000000	-0.5	38	256 qam	29
17	371000000	-0.4	40	256 qam	30
18	379000000	-0.7	38	256 qam	31
19	395000000	-1	38	256 qam	33
20	403000000	-1	38	256 qam	34
21	411000000	-1.2	38	256 qam	35
22	419000000	-1.7	38	256 qam	36
23	523000000	-5.5	37	256 qam	37
24	531000000	-6	37	256 qam	38
Downstream bonded channels
Channel	Locked Status	RxMER (dB)	Pre RS Errors	Post RS Errors
1	Locked	38.9	352	486
2	Locked	38.9	485	425
3	Locked	40.3	494	2239
4	Locked	38.9	429	723
5	Locked	38.9	412	676
6	Locked	38.9	434	604
7	Locked	38.6	488	611
8	Locked	38.9	428	605
9	Locked	38.9	462	596
10	Locked	38.6	455	640
11	Locked	38.9	446	675
12	Locked	38.6	432	758
13	Locked	38.6	425	737
14	Locked	38.9	390	703
15	Locked	38.9	396	654
16	Locked	38.6	380	689
17	Locked	40.3	381	705
18	Locked	38.6	354	653
19	Locked	38.9	331	673
20	Locked	38.9	350	601
21	Locked	38.9	373	662
22	Locked	38.6	403	769
23	Locked	37.6	1640	778
24	Locked	37.6	2393	711
Upstream bonded channels
Channel	Frequency (Hz)	Power (dBmV)	Symbol Rate (ksps)	Modulation	Channel ID
1	23600000	43.5	5120	64 qam	5
2	30100000	45	5120	64 qam	4
3	36600000	45	5120	64 qam	3
4	43100000	45	5120	64 qam	2
5	49600000	45	5120	64 qam	1
Upstream bonded channels
Channel	Channel Type	T1 Timeouts	T2 Timeouts	T3 Timeouts	T4 Timeouts
1	ATDMA	0	0	2	0
2	ATDMA	0	0	0	0
3	ATDMA	0	0	0	0
4	ATDMA	0	0	0	0
5	ATDMA	0	0	0	0

Things were pretty glitchy on Tuesday 3rd Oct:

[NeedsCoffee · Accepted solution]

Ok my issue is resolved. In the end instead of just tightening the connections, this time I disconnected the cables coming in to the house, cleaned the connectors thoroughly as well as the connection box outside, used WD40 to ensure no water contamination, and re-tightened everything with spanners to ensure tightness. Finally i also disconnected the TV lead at the splitter and terminated that connection with a proper terminator. Not had a problem since. There was a marked drop in max latency as well as packet loss dropping to near 0. No disconnections since and speed has improved too!

[Steven_L]

Thanks for coming back to us NeedsCoffee and I'm glad to hear that your issues have now been resolved.

Kind Regards,

Steven_L