Frequently failing internet connection

[simonjb]

Hello.

Since the end of last weekend my internet connection has been failing at least once a day.  Sometimes it's "just" a temporary (one minute or so) loss of connectivity (enough to kick me off a video call) but at other times the Superhub reboots itself.  Sometimes it doesn't recover again and I need to power cycle it.

The Superhub is running in modem mode, connected to a Netgear Orbi mesh system (which is working absolutely fine, as far as I can tell - I still have connectivity to local servers etc. in the house).

Reading other threads on this forum and looking at what's in the logs it appears that there might be "noise" on the coax line.  I've reported the problem to VM over the phone this morning (c.11.30); they said they have increased the power on the line but I'm not convinced that's the issue, and it certainly hasn't fixed the problem.

Superhub logs / config and BQM to follow.

This sounds like a physical cabling issue to me.  Does this need an engineer out to take a look?  Thanks in advance for any help.

[simonjb]

Hi,

I already have a BQM running.  Here's today's graph (the outage around 8am is when I did the factory reset of the hub, as requested yesterday):

https://www.thinkbroadband.com/broadband/monitoring/quality/share/645e550b9803d6e6c75aa6e02b59c9637cf9e7d2-24-06-2021

[simonjb]

...and here's yesterday's:

https://www.thinkbroadband.com/broadband/monitoring/quality/share/a89fa73eb923cd85d1a21ba5f63291c6a040c1c9-23-06-2021

[simonjb]

The internet connection has just failed again.  It really is very unstable.  Same messages as usual - I will post below for completeness.

Network Log

Time Priority Description

24/06/2021 14:31:39	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:39	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:39	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:39	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:37	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:37	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:37	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:37	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:37	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:37	Warning!	Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:37	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:36	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:35	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:33	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:32	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:32	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:31:32	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:30:18	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:30:18	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
24/06/2021 14:27:42	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

[simonjb]

Downstream and upstream data from the hub (NB the modem was power-cycled and factory reset at 8am this morning, so these error counts are after less than 8 hours):

Downstream bonded channels

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

1	370750000	-1.7	30	256 qam	26
2	202750000	1	31	256 qam	9
3	210750000	0.9	31	256 qam	10
4	218750000	0.7	31	256 qam	11
5	226750000	0.5	31	256 qam	12
6	234750000	0.7	31	256 qam	13
7	242750000	0.5	30	256 qam	14
8	250750000	0.2	30	256 qam	15
9	258750000	0.2	30	256 qam	16
10	266750000	0	30	256 qam	17
11	274750000	-0.4	30	256 qam	18
12	282750000	-0.5	30	256 qam	19
13	290750000	-0.5	30	256 qam	20
14	298750000	-0.5	30	256 qam	21
15	306750000	-0.7	30	256 qam	22
16	314750000	-0.7	30	256 qam	23
17	322750000	-0.9	30	256 qam	24
18	330750000	-0.9	30	256 qam	25
19	378750000	-2.5	30	256 qam	27
20	386750000	-2.7	30	256 qam	28
21	394750000	-2.5	30	256 qam	29
22	402750000	-2.4	30	256 qam	30
23	410750000	-2.5	30	256 qam	31
24	418750000	-2.4	30	256 qam	32

Downstream bonded channels

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

1	Locked	33.4	8384	390016
2	Locked	34.4	1718	1788277
3	Locked	34.3	1457	409485
4	Locked	34.4	1945	2078028
5	Locked	34.4	2157	411449
6	Locked	33.9	4106	3068132
7	Locked	33.8	6116	2477668
8	Locked	33.5	5965	86680
9	Locked	33.5	7853	3047330
10	Locked	33.4	7146	283043
11	Locked	33.4	8739	342096
12	Locked	33.3	12407	1047354
13	Locked	32.9	17261	3021355
14	Locked	33	14686	28612
15	Locked	33	13162	110744
16	Locked	33	12590	4400
17	Locked	33	11530	335128
18	Locked	33.3	9015	302868
19	Locked	33.3	7903	246260
20	Locked	33.4	6121	334971
21	Locked	33.4	8172	1556376
22	Locked	33.4	7634	461304
23	Locked	33.3	9157	1205714
24	Locked	33.3	8168	354569

Upstream bonded channels

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

1	39400000	42.3	5120	64 qam	6
2	25800000	40.8	5120	64 qam	8
3	32600000	42	5120	64 qam	7
4	46200000	44	5120	64 qam	5

Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

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

[simonjb]

From what I understand, the SNR on the downstream is too low - should be >34.  This seems odd as the engineer tested the line and couldn't find any problem last Saturday.  But looking back over the stats I've taken from the hub over the last couple of weeks, the SNR (in fact, all the figures) seem to vary a fair bit.  Is it possible that something is intermittently producing noise on the line? 

[David_Bn]

Thanks for coming back to us @simonjb,

I've requested that an engineer comes to revisit the property to take another look at the connection for you

Pleas log into your self-care account to view the time and date of the visit and you will be free to rearrange this if required

Kindest regards,

David_Bn

[simonjb]

Thank you David.

[simonjb]

Just an update after the engineer visit....

The engineer came a week ago and renewed all the cables and connectors, including removing a _very_ old CATV/FM radio splitter (I think the cable was installed to the house 30 years ago and hasn't been changed since).

Since the engineer visit the connection has been stable.  I can see very few errors in the log and the SNR is now 38 dB across all downstream channels.

I'm hopeful that this has fixed the problem, but will continue to monitor, especially if the weather gets hot again (there did seem to be some correlation between the worst problems and very hot weather).  Thanks everyone for your help.

Simon.

[lotharmat]

No problem!

Keep us posted! - The problems in hot weather can be caused by the expansion of the cable leading to a change in power levels - normally if you are firmly within the spec all is fine and you notice nothing - However if you are close to tolerance - a small change in power can tip over the edge and cause issues!

[Travis_M]

Be sure to keep us updated on this @simonjb 🙂

Glad to hear you've seen an improvement

Regards