SYNC Timing Synchronization failure - Cable Modem Reboot because of - kernel-panic

[Annuity8524]

Recently my connection has become very unstable, dropouts happen multiple times a day, even multiple times an hour sometimes.

The logs show many reboots due to kernel panic. Rebooting doesn't seem to make any difference.

Any help would be greatly appreciated.

04-11-2024 15:11:30	warning	MDD message timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 15:11:19	notice	REGISTRATION COMPLETE - Waiting for Operational status
04-11-2024 15:11:14	warning	RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 15:11:13	warning	RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 15:11:13	warning	Dynamic Range Window violation
04-11-2024 15:11:08	notice	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 15:11:07	notice	TLV-11 - unrecognized OID;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 15:11:00	warning	DHCP WARNING - Non-critical field invalid in response ;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 15:10:58	notice	Honoring MDD; IP provisioning mode = IPv4
04-11-2024 15:10:52	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 15:10:46	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 15:10:45	critical	Cable Modem Reboot because of - kernel-panic
04-11-2024 04:37:33	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 04:37:28	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
04-11-2024 04:37:27	critical	Cable Modem Reboot because of - kernel-panic
03-11-2024 21:30:19	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
03-11-2024 21:30:13	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
03-11-2024 21:30:13	critical	Cable Modem Reboot because of - kernel-panic
03-11-2024 19:56:47	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
03-11-2024 19:56:41	critical	Cable Modem Reboot because of - kernel-panic
03-11-2024 19:56:41	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
03-11-2024 18:58:15	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
03-11-2024 18:58:09	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
03-11-2024 18:58:09	critical	Cable Modem Reboot because of - kernel-panic
03-11-2024 15:40:57	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
03-11-2024 15:40:48	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
03-11-2024 15:40:42	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
03-11-2024 15:40:38	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;

3.0 Downstream channels

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

1	331000000	7.7	41	QAM 256	25
2	139000000	6.6	41	QAM 256	1
3	147000000	6.2	42	QAM 256	2
4	155000000	6.3	43	QAM 256	3
5	163000000	6.6	43	QAM 256	4
6	171000000	6.7	42	QAM 256	5
7	179000000	6.9	42	QAM 256	6
8	187000000	7	42	QAM 256	7
9	195000000	7.6	42	QAM 256	8
10	211000000	7.7	42	QAM 256	10
11	219000000	7.4	43	QAM 256	11
12	227000000	7	43	QAM 256	12
13	235000000	7.1	43	QAM 256	13
14	243000000	6.9	42	QAM 256	14
15	251000000	6.8	41	QAM 256	15
16	259000000	6.8	41	QAM 256	16
17	267000000	6.8	41	QAM 256	17
18	275000000	7.2	41	QAM 256	18
19	283000000	7.7	41	QAM 256	19
20	291000000	8.1	41	QAM 256	20
21	299000000	8.5	43	QAM 256	21
22	307000000	8.3	43	QAM 256	22
23	315000000	8.4	43	QAM 256	23
24	323000000	8	42	QAM 256	24
25	339000000	7.6	41	QAM 256	26
26	347000000	7	41	QAM 256	27
27	355000000	6.5	40	QAM 256	28
28	363000000	6	41	QAM 256	29
29	371000000	5.6	42	QAM 256	30
30	379000000	5.3	43	QAM 256	31
31	387000000	4.7	43	QAM 256	32

3.0 Downstream channels

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

1	Locked	41	1	0
2	Locked	41	0	0
3	Locked	42	0	0
4	Locked	43	0	0
5	Locked	43	0	0
6	Locked	42	0	0
7	Locked	42	0	0
8	Locked	42	0	0
9	Locked	42	0	0
10	Locked	42	0	0
11	Locked	43	0	0
12	Locked	43	0	0
13	Locked	43	0	0
14	Locked	42	0	0
15	Locked	41	0	0
16	Locked	41	0	0
17	Locked	41	0	0
18	Locked	41	0	0
19	Locked	41	0	0
20	Locked	41	1	0
21	Locked	43	0	0
22	Locked	43	0	0
23	Locked	43	2	0
24	Locked	42	0	0
25	Locked	41	0	0
26	Locked	41	2	0
27	Locked	40	1	0
28	Locked	41	4	0
29	Locked	42	4	0
30	Locked	43	3	0
31	Locked	43	7	0

3.1 Downstream channels

Channel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)

33

94

4K

1840

QAM 4096

1108

3.1 Downstream channels

Channel ID Locked Status RxMER Data (dB) PLC Power (dBmV) Corrected errors (Active Profile) Uncorrectable errors (Active Profile)

33

Locked

20

-29.6

1384717

38474720

3.0 Upstream channels

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

0	49600000	42.8	5120	QAM 64	1
1	43100000	41.8	5120	QAM 64	2
2	36600000	40.8	5120	QAM 64	3
3	30100000	39.8	5120	QAM 64	4
4	23600000	39.5	5120	QAM 64	9

3.0 Upstream channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

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

3.1 Upstream channels

Channel Channel Width (MHz) Power (dBmV) FFT Type Modulation

12

10.4

39.0

2K

QAM 256

3.1 Upstream channels

Channel Channel Type Number of Active Subcarriers First Active Subcarrier (Hz) T3 Timeouts T4 Timeouts

12

OFDMA

208

74000000

0

0

[Daniel_Et]

Hi @Annuity8524 👋 Thank you for your post and welcome to the Virgin Media Community 😀

We're sorry to hear about the problems you've been having 😔

Just to confirm, are you experiencing the same problems on devices connected via WiFi and ethernet cable?

Advice on how to fix internet problems can be found here.

Please pop back to us at your earliest convenience.

Regards,
Daniel

[Sephiroth]

I'm not sure that the Forum Understood what you were saying.  So I'll put it as a one liner (in CAPITALS) and then add some context.

THE OP IS SUFFERING MODEM REBOOTS DUE TO A "KERNEL PANIC" AS EVIDENCED IN THE LOGS.

The hub runs under Linux and the "Kernel Panic" is a Linux message that describes something that the hub's kernel processes (for critical errors) cannot handle.  The cause of that could be anything, ranging from faulty hardware, faulty error handling code, dodgy signals from an external device.

I've noticed that your Docsis 3.1 downstream is totally borked (see poer levels, SNR and uncorrected errors) and that could be the problem.  @FORUMTEAM

[Annuity8524]

Thank you for this.

Virgin support have been absolutley clueless everytime I mention kernel panic to them, nobody even seems to understand what the kernel is.

I am equally clueless about Docsis, do you think the best bet is to try and get an engineer out?

[Sephiroth]

If your downstream still shows this:

3.1 Downstream channels

Channel ID Locked Status RxMER Data (dB) PLC Power (dBmV) Corrected errors (Active Profile) Uncorrectable errors (Active Profile)

33

Locked

20

-29.6

1384717

38474720

with figures like I've highlighted in red, then your circuit is in trouble.

A technician needs to attend and then report the anomalous downstream to Network Team if it's still present.  The Forum Team can arrange the visit if they accept what I've said.

[Kath_P]

Hi Annuity8524, 

Thanks for coming back to us on this one. Before we can arrange an engineer, we still need to go through the usual diagnostics. We've not been able to locate your account based on your forum credentials. We will need to confirm some information with you in order for us to proceed with checks. 

I have sent you a direct message to allow us to do this with you in a private space. If you are using a PC/Laptop then you can just click on the little ✉ at the top right-hand side of the page to access your inbox. If you are on a mobile/tablet device then instead click on the little circle icon in the top right then select 'Messages'. 😊

Thanks,