For the past few weeks, my WiFi drops regularly and the modem occasionally reboots. The router log shows multiple entries for the following. Does this require an engineer visit as I have read? SYNC Timing Synchronization failure - Failed to acquireQAM/QPSK symbol timing;;CM-

Hi SteveyW123, Thanks for taking the time to contact us via the Community. It's lovely having you on board with us in the Forums. ⭐ We're sorry to hear you're having issues with your WiFi connection and disconnections. Checking things here, there is no open fault affecting you. The hub is looking good in terms of power and signal levels however we can see quite a high number of disconnections. We won't be able to fix this remotely so I would like to arrange for an engineer to come to take a look at this for you. I just need to confirm the address to ensure we are booking the visit on the correct account. I have sent you a direct message to allow us to do this with you in a private space. Just click on the little ✉ at the top right-hand side of the page to access your inbox. 😊 Thanks,

Regular dropout of WiFi and Modem Reboot | Virgin Media Community

8 Replies

jbrennand

Very Insightful Person

23 days ago

Post up all of the hub data...

just copy/paste the normal “Formatted Text” (not images) 3 FULL sets of data onto here – 2 tables in the Downstream tab, the 2 in the Upstream tab, & the Network Logs pages. 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

Also, just check for a known fault on the “free & automated” Service Status number - 0800 561 0061 - which usually gives the most up to date info. and tells you of more local issues and fix estimates, down to street cab/ postcode level.

SteveyW123

Joining in

22 days ago

Downstream

Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
1	347000000	6	40	QAM 256	27
2	139000000	6	39	QAM 256	1
3	147000000	6	39	QAM 256	2
4	155000000	6	40	QAM 256	3
5	163000000	6	40	QAM 256	4
6	171000000	5.9	40	QAM 256	5
7	179000000	6	39	QAM 256	6
8	187000000	6.1	39	QAM 256	7
9	195000000	6.2	39	QAM 256	8
10	203000000	6.2	39	QAM 256	9
11	211000000	6.3	40	QAM 256	10
12	219000000	6.2	40	QAM 256	11
13	227000000	6.2	40	QAM 256	12
14	235000000	6.1	40	QAM 256	13
15	243000000	6	40	QAM 256	14
16	251000000	5.9	39	QAM 256	15
17	259000000	5.9	39	QAM 256	16
18	267000000	6	39	QAM 256	17
19	275000000	6	40	QAM 256	18
20	283000000	6	40	QAM 256	19
21	291000000	6.1	40	QAM 256	20
22	299000000	6.1	40	QAM 256	21
23	307000000	6.1	40	QAM 256	22
24	315000000	6	39	QAM 256	23
25	323000000	5.8	39	QAM 256	24
26	331000000	5.6	40	QAM 256	25
27	339000000	5.8	40	QAM 256	26
28	355000000	6	40	QAM 256	28
29	363000000	6	40	QAM 256	29
30	371000000	6.1	39	QAM 256	30
31	379000000	6.2	39	QAM 256	31
32	387000000	6.1	39	QAM 256	32

Channel	Locked Status	RxMER (dB)
1	Locked	40
2	Locked	39
3	Locked	39
4	Locked	40
5	Locked	40
6	Locked	40
7	Locked	39
8	Locked	39
9	Locked	39
10	Locked	39
11	Locked	40
12	Locked	40
13	Locked	40
14	Locked	40
15	Locked	40
16	Locked	39
17	Locked	39
18	Locked	39
19	Locked	40
20	Locked	40
21	Locked	40
22	Locked	40
23	Locked	40
24	Locked	39
25	Locked	39
26	Locked	40
27	Locked	40
28	Locked	40
29	Locked	40
30	Locked	39
31	Locked	39
32	Locked	39

Channel	Channel Width (MHz)	FFT Type	Number of Active Subcarriers	Modulation (Active Profile)	First Active Subcarrier (Hz)
159	94	4K	1840	QAM 4096	1108

Channel ID	Locked Status	RxMER Data (dB)	PLC Power (dBmV)	Corrected errors (Active Profile)	Uncorrectable errors (Active Profile)
159	Locked	0	7.8	1459775777	0

SteveyW123

Joining in

22 days ago

Upstream

Channel	Frequency (Hz)	Power (dBmV)	Symbol Rate (ksps)	Modulation	Channel ID
0	60300000	33.5	5120	QAM 64	9
1	53700000	34	5120	QAM 64	10
2	46200000	34	5120	QAM 64	11
3	39400000	33.5	5120	QAM 64	12
4	32600000	34.3	5120	QAM 64	13
5	23600000	34	5120	QAM 64	14

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	0	0
5	ATDMA	0	0	0	0

SteveyW123

Joining in

22 days ago

Logs

Time	Priority	Description
17-11-2025 15:53:26	warning	DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
17-11-2025 15:42:22	notice	REGISTRATION COMPLETE - Waiting for Operational status
17-11-2025 15:42:16	warning	REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
17-11-2025 15:42:11	notice	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
17-11-2025 15:42:08	warning	DHCP WARNING - Non-critical field invalid in response ;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
17-11-2025 15:42:06	notice	Honoring MDD; IP provisioning mode = IPv4
17-11-2025 15:41:56	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
17-11-2025 15:41:56	critical	Cable Modem Reboot because of - HW or Power-On Reset
17-11-2025 15:12:07	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
17-11-2025 15:12:05	critical	Cable Modem Reboot because of - unknown
16-11-2025 21:15:25	critical	No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 21:14:05	critical	No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 21:13:47	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:16:54	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:16:19	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:16:19	critical	16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:16:15	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:16:13	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:15:45	critical	No Ranging Response received - T3 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:15:42	critical	No Ranging Response received - T3 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 15:02:27	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 15:02:27	critical	Cable Modem Reboot because of - unknown
15-11-2025 20:36:17	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
15-11-2025 20:36:17	critical	16 consecutive T3 timeouts while trying to range on upstream channel 5;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
15-11-2025 20:26:18	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
15-11-2025 20:26:09	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
15-11-2025 20:26:09	critical	16 consecutive T3 timeouts while trying to range on upstream channel 0;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
15-11-2025 20:26:07	critical	No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
15-11-2025 20:26:07	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
15-11-2025 20:26:04	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
15-11-2025 20:26:03	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;
15-11-2025 20:25:58	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=30:67:a1:d0:29:ff;CMTS-MAC=0c:11:67:02:5b:21;CM-QOS=1.1;CM-VER=3.1;

SteveyW123

Joining in

21 days ago

Time	Priority	Description
18-11-2025 16:03:02	warning	DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-;CMTS-M;CM-QOS=1.1;CM-VER=3.1;
18-11-2025 15:51:58	notice	REGISTRATION COMPLETE - Waiting for Operational status
18-11-2025 15:51:52	warning	REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
18-11-2025 15:51:47	notice	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
18-11-2025 15:51:44	warning	DHCP WARNING - Non-critical field invalid in response ;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
18-11-2025 15:51:42	notice	Honoring MDD; IP provisioning mode = IPv4
18-11-2025 15:51:31	critical	Cable Modem Reboot because of - unknown
18-11-2025 15:51:31	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
17-11-2025 15:41:56	critical	Cable Modem Reboot because of - HW or Power-On Reset
17-11-2025 15:41:56	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
17-11-2025 15:12:07	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
17-11-2025 15:12:05	critical	Cable Modem Reboot because of - unknown
16-11-2025 21:15:25	critical	No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 21:14:05	critical	No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 21:13:47	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:16:54	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:16:19	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;
16-11-2025 19:16:19	critical	16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-;CMTS-;CM-QOS=1.1;CM-VER=3.1;

Kath_P
Forum Team
19 days ago
Hi SteveyW123,

Thanks for taking the time to contact us via the Community. It's lovely having you on board with us in the Forums. ⭐

We're sorry to hear you're having issues with your WiFi connection and disconnections. Checking things here, there is no open fault affecting you. The hub is looking good in terms of power and signal levels however we can see quite a high number of disconnections.

We won't be able to fix this remotely so I would like to arrange for an engineer to come to take a look at this for you.

I just need to confirm the address to ensure we are booking the visit on the correct account. I have sent you a direct message to allow us to do this with you in a private space. Just click on the little ✉ at the top right-hand side of the page to access your inbox. 😊

Thanks,

Client62
Alessandro Volta
22 days ago
Which model of VM Hub is behaving like this ?
- SteveyW123
  Joining in
  22 days ago
  It’s the Hub 5.

Forum Discussion

Regular dropout of WiFi and Modem Reboot

8 Replies

Related Content

Regular drops in speed and repeated router reboots

Dropouts

Intermittent Broadband dropouts and latency

Regular dropouts

Frequent connectivity dropout using GlobalProtect VPN