Broadband connection keeps dropping

[JoannaLB]

Hi

I'm experiencing constant drops of internet connection recently. The issue started a week or two ago and it's progressively getting worse. Today since I started logging network status at 11:30 I already had 27 disconnects. The disconnects are rather short, but very disruptive for remote work. Please see attached screenshot of a log.

I already called support twice, who unfortunately couldn't help much, apart from offering WiFi booster, which is not a fix to hub losing internet connection. Devices linked via Ethernet lose connection too. 
I have Hub4 and no other router. Things I tried already:
resetting the hub to factory settings
updating hub firmware
checking if the cable is secured correctly

checked the service status in the area - all looks fine

Unfortunately nothing helps and the network is practically unusable now. I actually got worse after I called the helpdesk...
Even sending this message was a pain as I was disconnected again...

[Tudor · Accepted solution]

Please supply some stats, instructions follow:

How to get stats from a VM hub (no need to logon to the hub)

Open a web browser and go to 192.168.0.1 router mode or 192.168.100.1 modem mode

• Click on the “> Check router status” button
• Click on the “Downstream” tab, copy the text and paste into your reply, do not take a screen shot
• Click on the “Upstream” tab, copy the text and paste into your reply
• Click on the “Networking” tab, copy the text and paste into your reply.
• Do NOT post photos or screen shots they will be rejected as they contain MAC addresses. The board software will automatically change MAC addresses to **:** if done as above.

[JoannaLB]

Hi Tudor,

Thanks for the reply. Here's the stats you asked about: 

3.0 Downstream channels
Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID
26 339000000 0.8 37.4 QAM256 26
1 139000000 3.6 36.4 QAM256 1
2 147000000 3 36.4 QAM256 2
3 155000000 3.3 35.8 QAM256 3
4 163000000 4 35.8 QAM256 4
5 171000000 2.9 35.8 QAM256 5
6 179000000 3.1 35.8 QAM256 6
7 187000000 1.7 35.8 QAM256 7
8 195000000 1.9 35.8 QAM256 8
9 203000000 0.9 35.8 QAM256 9
10 211000000 0.8 35.8 QAM256 10
11 219000000 1.1 35.6 QAM256 11
12 227000000 1.1 35.8 QAM256 12
13 235000000 1.1 35.8 QAM256 13
14 243000000 0.3 35.8 QAM256 14
15 251000000 0.1 35.8 QAM256 15
16 259000000 -0.4 36.6 QAM256 16
17 267000000 0.5 36.4 QAM256 17
18 275000000 -0.3 36.4 QAM256 18
19 283000000 1.5 36.6 QAM256 19
20 291000000 -0.2 36.6 QAM256 20
21 299000000 1.9 36.6 QAM256 21
22 307000000 1.4 37.4 QAM256 22
23 315000000 2.2 37.4 QAM256 23
24 323000000 0.9 37.4 QAM256 24
25 331000000 2.3 37.6 QAM256 25
27 347000000 2.7 37.6 QAM256 27
28 355000000 0.4 37.4 QAM256 28
29 363000000 2.7 37.4 QAM256 29
30 371000000 1.8 37.4 QAM256 30
31 379000000 3.2 37.6 QAM256 31

3.0 Downstream channels
Channel Lock Status RxMER (dB) Pre RS Errors Post RS Errors
26 Locked 37.355988 0 0
1 Locked 36.386890 0 0
2 Locked 36.386890 0 0
3 Locked 35.779911 0 0
4 Locked 35.779911 0 0
5 Locked 35.779911 0 0
6 Locked 35.779911 0 0
7 Locked 35.779911 0 0
8 Locked 35.779911 0 0
9 Locked 35.779911 0 0
10 Locked 35.779911 0 0
11 Locked 35.595078 0 0
12 Locked 35.779911 0 0
13 Locked 35.779911 0 0
14 Locked 35.779911 0 0
15 Locked 35.779911 0 0
16 Locked 36.609653 0 0
17 Locked 36.386890 0 0
18 Locked 36.386890 0 0
19 Locked 36.609653 0 0
20 Locked 36.609653 0 0
21 Locked 36.609653 0 0
22 Locked 37.355988 0 0
23 Locked 37.355988 0 0
24 Locked 37.355988 0 0
25 Locked 37.636276 0 0
27 Locked 37.636276 0 0
28 Locked 37.355988 0 0
29 Locked 37.355988 0 0
30 Locked 37.355988 0 0
31 Locked 37.636276 0 0

3.1 Downstream channels
Channel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)
33 96 4K 1840 QAM4096 424

3.1 Downstream channels
Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)
33 Locked 39 1.5 17483946 11555

3.0 Upstream channels
Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID
1 36600000 38.5 5120 KSym/sec QAM64 3
2 43100000 39.3 5120 KSym/sec QAM64 2
3 23600000 36 5120 KSym/sec QAM64 9
4 30100000 37.3 5120 KSym/sec QAM64 4
5 49600000 38.3 5120 KSym/sec QAM64 1

3.0 Upstream 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
5 ATDMA 0 0 0 0

3.1 Upstream channels
Channel Channel Width (MHz) Power (dBmV) FFT Type Modulation
10 10.8 42.3 2K QAM128

3.1 Upstream channels
Channel Channel Type Number of Active Subcarriers First Active Subcarrier (Hz) T3 Timeouts T4 Timeouts
10 OFDMA 220 53.4 0 0

Network log

Time Priority Description
Wed 29/11/2023
08:04:43 6 CM-STATUS message sent. Event Type Code: 24; Chan ID: 33; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:04:05 5 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Thu 01/01/1970
00:01:36 3 No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Thu 01/01/1970
00:01:35 3 Unicast Ranging Received Abort Response - initializing MAC;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Thu 01/01/1970
00:01:21 3 No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Thu 01/01/1970
00:01:21 3 Unicast Ranging Received Abort Response - initializing MAC;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:44 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:43 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:32 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:29 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:09 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:08 6 CM-STATUS message sent. Event Type Code: 2; Chan ID: 3; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:07 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:06 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:06 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
08:00:03 6 CM-STATUS message sent. Event Type Code: 16; Chan ID: 33; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:54 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:51 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:35 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:35 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:26 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:23 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:10 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:07 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:04 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:59:04 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:58:51 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:58:50 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:58:37 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:58:35 6 CM-STATUS message sent. Event Type Code: 2; Chan ID: 2; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:58:22 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:58:21 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 12; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:43 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:42 6 CM-STATUS message sent. Event Type Code: 4; Chan ID: 3; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:38 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:38 6 CM-STATUS message sent. Event Type Code: 16; Chan ID: 33; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:35 5 Lost MDD Timeout;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:34 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:33 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 10; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:30 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:30 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 10; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:57:12 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:28:16 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 10; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:27:38 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:27:37 3 No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:27:31 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:27:31 6 CM-STATUS message sent. Event Type Code: 5; Chan ID: 10; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:26:51 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:26:51 3 No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
Wed 29/11/2023
07:26:05 3 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;

[JoannaLB]

I've done some research on these forums and I found this thread: 

https://community.virginmedia.com/t5/Networking-and-WiFi/SYNC-Timing-Synchronization-failure-Loss-of...

and this was one of the answers:

"Synchronisation failure is where the hub can't maintain a lock on one or more of the 28 channels it uses to connect with the gear in the street cabinet.  And when it does lose synch, that loss of one or more channels becomes a "partial service".  What that means for the customer is slowdowns, disconnection and poor latency.  The hub does try and renegotiate the lost channel, but that takes time, and the problem will recur.

The underlying cause is usually noise on the upstream, because it is those channels that the hub uses to communicate with the gear in the street cabinet.  The upstream looks OK on the data you've posted, but that's most likely because you've recently rebooted the hub (I can tell that from the low error counts).  Rebooting causes the hub to renegotiate all 28 channels, and usually provides a temporary fix, but because the underlying cause isn't fixed, it will recur.  Replacing the hub won't make a blind bit of difference - that's a cheap fix by agents who know nothing about the technology.  If they'd looked at your network log and knew what it meant they'd have sent out a technician to find the real problem." 

It seems to describe my issue exactly. Rebooting the hub works for a moment and then all the issues come back

[Tudor]

There does not appear to be any noise on the circuit and whilst the SNR is on the low side it’s within spec.  Next 

Setup a Broadband Quality Monitor and post a link to your live graph. It monitors your connection 24/7 and provides diagnosis of any underlying issues