Always One Channel High SNR

[Greenpalmer]

I always seem to have one downstream channel with high noise - it's always either channel 4 or channel 12 with a bit of overspill into adjacent channels.

Every time I reboot the router within a very short time channel 4 or 12 goes down to 33.

Also I often get only 16 or 32 qam on upsteam channels instead of the regular 64.

Router stats and log follow:

Downstream bonded channels

Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
1	203000000	4.3	37	256 qam	9
2	139000000	6.8	37	256 qam	1
3	147000000	6	37	256 qam	2
4	155000000	6	37	256 qam	3
5	163000000	5.5	37	256 qam	4
6	171000000	5.5	37	256 qam	5
7	179000000	5	37	256 qam	6
8	187000000	5	37	256 qam	7
9	195000000	4.6	37	256 qam	8
10	211000000	4.1	37	256 qam	10
11	219000000	3.7	34	256 qam	11
12	227000000	3.7	33	256 qam	12
13	235000000	3.2	37	256 qam	13
14	243000000	3.2	37	256 qam	14
15	251000000	2.9	37	256 qam	15
16	259000000	3	37	256 qam	16
17	267000000	2.7	37	256 qam	17
18	275000000	2.4	37	256 qam	18
19	283000000	1.9	37	256 qam	19
20	291000000	1.2	37	256 qam	20
21	299000000	1.2	36	256 qam	21
22	307000000	1.9	37	256 qam	22
23	315000000	2.5	37	256 qam	23
24	323000000	2.9	37	256 qam	24

Downstream bonded channels

Channel	Locked Status	RxMER (dB)	Pre RS Errors	Post RS Errors
1	Locked	37.3	1449	648
2	Locked	37.3	2452	542
3	Locked	37.3	1108	572
4	Locked	37.6	1346	12888
5	Locked	37.6	997	1002
6	Locked	37.6	1249	963
7	Locked	37.3	1103	1049
8	Locked	37.3	917	823
9	Locked	37.3	773	833
10	Locked	37.6	818	699
11	Locked	34.3	1145020	563
12	Locked	33.9	4226461	848
13	Locked	37.3	1209	490
14	Locked	37.3	700	421
15	Locked	37.3	744	515
16	Locked	37.3	1357	503
17	Locked	37.6	918	533
18	Locked	37.6	937	480
19	Locked	37.6	1059	608
20	Locked	37.3	1782	550
21	Locked	36.6	1968	560
22	Locked	37.3	1079	764
23	Locked	37.6	1409	710
24	Locked	37.6	712	742

Upstream bonded channels

Channel	Frequency (Hz)	Power (dBmV)	Symbol Rate (ksps)	Modulation	Channel ID
1	39400053	48	5120	64 qam	4
2	53700200	49	5120	32 qam	2
3	46199912	48.5	5120	16 qam	3
4	60300010	49.3	5120	64 qam	1

Upstream bonded channels

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

Network Log

Time	Priority	Description
21/08/2021 07:43:22	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
21/08/2021 02:01:4	Error	DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/08/2021 15:24:48	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
19/08/2021 09:40:48	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
17/08/2021 14:59:32	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
17/08/2021 14:01:4	Error	DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
15/08/2021 17:06:21	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
15/08/2021 07:10:48	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
14/08/2021 21:04:55	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
14/08/2021 02:01:4	Error	DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/08/2021 00:11:28	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
11/08/2021 17:48:2	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
11/08/2021 13:16:11	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
11/08/2021 11:51:52	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
10/08/2021 16:50:40	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
10/08/2021 14:01:3	Error	DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
09/08/2021 05:07:48	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
08/08/2021 00:53:34	notice	LAN login Success;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/08/2021 02:01:3	Error	DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
06/08/2021 16:13:24	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

[Greenpalmer]

Thanks for the update John.

I'll check again on 10th September.

[Ayisha_B]

Hi @Greenpalmer,

Still showing as 09 SEP 2021 09:00. Let us know if there's any issues after this. 

Kind Regards

[Greenpalmer]

Hi Ayisha,

It's now several days after the fault fix date and if anything the problem is getting worse.

See the stats, and notice all the error messages in the Network Log:

Downstream bonded channels

Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
1	299000000	0.7	37	256 qam	21
2	203000000	1.9	37	256 qam	9
3	211000000	1.9	37	256 qam	10
4	219000000	1.7	33	256 qam	11
5	227000000	1.5	32	256 qam	12
6	235000000	1.2	37	256 qam	13
7	243000000	1.4	37	256 qam	14
8	251000000	1.2	37	256 qam	15
9	259000000	1.4	37	256 qam	16
10	267000000	1.2	37	256 qam	17
11	275000000	1	38	256 qam	18
12	283000000	0.7	37	256 qam	19
13	291000000	0.4	37	256 qam	20
14	307000000	1.5	37	256 qam	22
15	315000000	2	38	256 qam	23
16	323000000	2.5	38	256 qam	24
17	331000000	2.2	38	256 qam	25
18	339000000	2.2	38	256 qam	26
19	347000000	2.2	38	256 qam	27
20	355000000	2	38	256 qam	28
21	363000000	1.7	38	256 qam	29
22	371000000	1.7	38	256 qam	30
23	379000000	1.2	38	256 qam	31
24	387000000	1.4	38	256 qam	32

Downstream bonded channels

Channel	Locked Status	RxMER (dB)	Pre RS Errors	Post RS Errors
1	Locked	37.6	16	12
2	Locked	37.6	16	16
3	Locked	37.6	15	16
4	Locked	33.4	4814127	7436330
5	Locked	32.9	4773509	7519336
6	Locked	37.3	13	16
7	Locked	37.6	20	13
8	Locked	37.6	15	10
9	Locked	37.6	19	12
10	Locked	37.6	12	13
11	Locked	38.6	12	16
12	Locked	37.6	14	13
13	Locked	37.6	14	14
14	Locked	37.6	23	0
15	Locked	38.6	15	8
16	Locked	38.6	22	9
17	Locked	38.9	21	12
18	Locked	38.6	26	12
19	Locked	38.6	32	0
20	Locked	38.6	22	14
21	Locked	38.6	13	12
22	Locked	38.9	24	0
23	Locked	38.6	12	12
24	Locked	38.6	23

Upstream bonded channels

Channel	Frequency (Hz)	Power (dBmV)	Symbol Rate (ksps)	Modulation	Channel ID
1	39400000	49.8	5120	64 qam	4
2	46200000	49.8	5120	64 qam	3
3	53700000	49.5	5120	64 qam	2
4	32600000	49.3	5120	64 qam	5

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 Log

Time	Priority	Description
16/09/2021 10:17:55	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:17:52	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:16:19	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:16:9	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:15:55	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:15:49	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:15:7	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:15:5	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:13:39	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:13:14	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:12:19	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:12:0	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 10:11:34	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 09:52:45	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 09:52:43	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 09:51:3	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 09:51:2	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 09:50:26	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 09:50:22	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
16/09/2021 09:50:11	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

[Steven_L]

Thanks for coming back to us @Greenpalmer.

I have looked into your account and can see that the estimated fix time has been extended to Monday 20th September at 16:30.

Regards,

Steven_L

[Tudor]

The two channels that are causing your trouble are in the DAB radio band, so I expect the problem is some noise ingress somewhere in the VM network local to you. This type of problem is difficult to trace.

[Greenpalmer]

@Steven_L - thanks for the info, will check again after the fix date/time but am not optimistic as this has been going on a long time with the fix date always being moved into the future.

@Tudor - thanks for your input, that's interesting. Sometimes the problem is on channel 4, other times on channel 12 - are they the two channels you are saying are channels associated with DAB radio, or are you saying they are the current problematic channels 4 and 5?

[Zak_M]

Good afternoon @Greenpalmer, 

Just popping past,  I can see that the SNR issue has been pushed back further, this is due to be resolved today, however as you have noticed by now, they are susceptible to being pushed back as they are notoriously difficult to find. 

Kind regards,

Zak_M 

[Greenpalmer]

Since I last posted quite a lot has happened. Things went completely haywire and the connection completely failed so an engineer came to visit.

He replaced the hub and did some work on the line outside the house and as a result things became quite a bit better.

However now the service quality is deteriorating again and I have noticed a few things from monitoring the BQM and router logs:

1. I only have 22 downstream channels, not the usual 24.
2. The upstream power levels are very high.
3. The hub reboots itself every night between 1am and 2am.
4. There are some strange entries (not the usual errors and warnings) in the hub log.

Here are the router stats:

Downstream bonded channels

Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
1	203000000	0	37	256 qam	9
2	139000000	3.2	36	256 qam	1
3	147000000	2.5	37	256 qam	2
4	155000000	2.5	38	256 qam	3
5	163000000	2.5	37	256 qam	4
6	171000000	2.5	38	256 qam	5
7	179000000	1.5	38	256 qam	6
8	187000000	0.7	37	256 qam	7
9	195000000	0	37	256 qam	8
10	211000000	0	37	256 qam	10
11	235000000	-1.2	37	256 qam	13
12	243000000	-1.2	37	256 qam	14
13	251000000	-0.9	37	256 qam	15
14	259000000	-1	37	256 qam	16
15	267000000	-1	37	256 qam	17
16	275000000	-1.4	37	256 qam	18
17	283000000	-1.5	38	256 qam	19
18	291000000	-2	37	256 qam	20
19	299000000	-1.7	37	256 qam	21
20	307000000	-1.2	37	256 qam	22
21	315000000	0.4	38	256 qam	23
22	323000000	0.9	38	256 qam	24

Downstream bonded channels

Channel	Locked Status	RxMER (dB)	Pre RS Errors	Post RS Errors
1	Locked	37.6	69	0
2	Locked	36.6	2260	7378
3	Locked	37.6	776	45
4	Locked	38.6	132	0
5	Locked	37.6	472	320
6	Locked	38.6	593	366
7	Locked	38.6	567	164
8	Locked	37.6	366	8
9	Locked	37.6	192	0
10	Locked	37.6	91	0
11	Locked	37.3	71	0
12	Locked	37.6	79	0
13	Locked	37.3	142	0
14	Locked	37.3	143	0
15	Locked	37.6	116	0
16	Locked	37.6	217	0
17	Locked	38.6	93	0
18	Locked	37.6	106	0
19	Locked	37.6	238	0
20	Locked	37.3	286	0
21	Locked	38.9	349	0
22	Locked	38.6	235	0

Upstream bonded channels

Channel	Frequency (Hz)	Power (dBmV)	Symbol Rate (ksps)	Modulation	Channel ID
1	32599834	51	5120	64 qam	5
2	39400087	51	5120	64 qam	4
3	46200000	52	5120	16 qam	3
4	25800148	51	5120	64 qam	11

Upstream bonded channels

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

Network Log

Time	Priority	Description
29/10/2021 08:24:37	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:23:25	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:22:48	critical	REG RSP not received;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:22:48	Error	T6 Timeout and retries exceeded;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:22:48	critical	Registration RSP rejected unspecified reason;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:22:48	critical	Registration RSP rejected message syntax error;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:21:58	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:17:19	critical	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:14:44	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:14:39	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:14:38	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 08:14:38	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 07:51:24	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
29/10/2021 07:49:50	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
28/10/2021 10:17:58	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
28/10/2021 10:17:55	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
28/10/2021 10:17:36	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
28/10/2021 10:17:36	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
28/10/2021 09:03:24	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
28/10/2021 09:03:23	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

[Tudor]

You need the technician back. All the upstream channels are too high and one is on 16QAM when it should be 64QAM. Also the Pre & Post RS errors are too high,

[Beth_G]

Hi Greenpalmer,

I am terribly sorry to hear these issue have still been ongoing, I appreciate it must be frustrating for you.

I have arranged a second visit for you as Tudor is right - your upstream channels are too high. Please sign into your My Virgin Media account to view your appointment time slot

Please do keep us posted with how the visit goes.

Kind regards

Beth