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Constant, frequent dropouts and packet loss

Recently had an issue with our Superhub 2ac, which Virgin kindly sent a replacement Superhub 3 for. All has been well for a few days, but now we are getting ridiculous packet loss.

BQM graph for the last 24 hours.

https://www.thinkbroadband.com/broadband/monitoring/quality/share/1f22f0879c94f40c4dc9f0f1d0ca30fdef208357-07-07-2020

With 2 of us working from home, and myself indulging in some late night gaming, this is really starting to get on our nerves. The drops are frequent, but only (usually) for less than a minute.

When using Discord (web chat service) and the drop occurs, I can still hear those on the call with me, but they cant hear me, suggesting its only TX side packet loss, not RX. 

Is the most likely cuplrit the new Superhub, or is there something else that could be causing it?

Superhub is running in modem mode, into UniFi Security Gateway, then from there into the home network.

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Alessandro Volta
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Message 2 of 14
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Re: Constant, frequent dropouts and packet loss

Post the Network, Upstream and Downstream logs back as text from the hubs admin pages

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Re: Constant, frequent dropouts and packet loss

Downstream bonded channels

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

1203000000-1.537256 qam9
2187000000-1.737256 qam7
3195000000-1.538256 qam8
4211000000-1.737256 qam10
5219000000-237256 qam11
6227000000-2.237256 qam12
7235000000-2.437256 qam13
8243000000-2.538256 qam14
9251000000-2.237256 qam15
10259000000-1.737256 qam16
11267000000-1.237256 qam17
12275000000-138256 qam18
13283000000-0.738256 qam19
14291000000-0.438256 qam20
15299000000-0.237256 qam21
16307000000038256 qam22
173150000000.438256 qam23
183230000000.938256 qam24
194430000000.238256 qam25
20451000000-0.437256 qam26
21459000000-0.438256 qam27
22467000000-0.438256 qam28
23475000000-0.238256 qam29
24483000000-0.537256 qam30



Downstream bonded channels

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

1Locked37.633563223356073
2Locked37.640862873890777
3Locked38.934508893494108
4Locked37.637179823498399
5Locked37.937243123457106
6Locked37.637265203401728
7Locked37.632613033149375
8Locked38.631933763034762
9Locked37.635872553084383
10Locked37.634338912837015
11Locked37.633233182674806
12Locked38.232010212467465
13Locked38.931067842301797
14Locked38.630288792152351
15Locked37.630190882096748
16Locked38.929262141919236
17Locked38.628493881788501
18Locked38.627668371631569
19Locked38.91936290659492
20Locked37.62014363670337
21Locked38.61979481644086
22Locked38.21943507622461
23Locked38.61881820583679
24Locked37.61899286579245

 

Upstream bonded channels

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

1325999665.1512064 qam5
2393999935.1512064 qam4
3462000065.1512064 qam3
4536999745.1512064 qam2



Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0000
2ATDMA0000
3ATDMA0000
4ATDMA0000
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Re: Constant, frequent dropouts and packet loss

Network Log

Time Priority Description

07/07/2020 10:32:8criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:32:1Warning!LAN login FAILED : Incorrect Username / Password / ConnectionType;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:31:58Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:31:56Warning!LAN login FAILED : Incorrect Username / Password / ConnectionType;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:31:56Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:31:53Warning!LAN login FAILED : Incorrect Username / Password / ConnectionType;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:31:53Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:31:53criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:31:53Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:31:50Warning!LAN login FAILED : Incorrect Username / Password / ConnectionType;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:30:34Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:30:32criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:09:7Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:09:7criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:08:27Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:08:27criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:07:29Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:07:28criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:07:18Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 10:07:2criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
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Message 5 of 14
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Helpful Answer

Re: Constant, frequent dropouts and packet loss

Your upstream power levels are too high, causing high downstream error levels and interrupting the hub's communications with the VM network gear.  I've flagged this for the forum staff who will be able to advise if this is a known area problem, or arrange a technician visit if needed.

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Message 6 of 14
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Re: Constant, frequent dropouts and packet loss

Can you check that all the coax cables are tight at both ends?

It might be worth powering the hub off, unscrewing the coax cable at both ends then re-seating and tightening them again.

Power back on the hub and post the same stats again.

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Message 7 of 14
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Re: Constant, frequent dropouts and packet loss

I can do that once the wife has finished her call, but I did that last night as part of my troubleshooting.

Unscrewed, checked and reseated all cables, from the wall to the splitter, then splitter to router.

Also checked the attenuators, of which there are 3 fitted to the line. 2x 3dB between the wall and the splitter, and a 6dB between the splitter and the router.

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Message 8 of 14
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Re: Constant, frequent dropouts and packet loss

Chances are that the attenuators need checking out, because your high upstream power levels suggest the return path is too heavily attenuated, to the point that the network gear can't communicate with the hub properly.  That might mean removing a "plain" attenuator and/or replacing with a forward path attenuator.  

You could experiment by alternately removing each in turn seeing if it makes a difference, but I would suggest that (unless you've got some experience of dealing with RF kit) you don't fiddle, because DOCSIS cable is a fickle beast and it is easy to make things worse.  It's on VM's side of the hub, so let a network technician either do the work, or if there are any on the forum they may be able to talk you through trial removal of selected attenuators, and checking what works.

 

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Re: Constant, frequent dropouts and packet loss

Downstream bonded channels

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

12030000001.438256 qam9
21870000001.738256 qam7
31950000001.538256 qam8
4211000000138256 qam10
52190000000.538256 qam11
62270000000.237256 qam12
7235000000037256 qam13
8243000000-0.538256 qam14
9251000000-0.538256 qam15
10259000000037256 qam16
112670000000.238256 qam17
122750000000.438256 qam18
132830000000.538256 qam19
142910000000.938256 qam20
152990000000.937256 qam21
16307000000138256 qam22
173150000001.538256 qam23
183230000001.738256 qam24
19443000000038256 qam25
20451000000-0.537256 qam26
21459000000-0.537256 qam27
22467000000-0.738256 qam28
23475000000-0.538256 qam29
24483000000-0.937256 qam30



Downstream bonded channels

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

1Locked38.633513554
2Locked38.68841174
3Locked38.68741162
4Locked38.68151155
5Locked38.68521085
6Locked37.38271056
7Locked37.68081075
8Locked38.98041055
9Locked38.68021027
10Locked37.6754998
11Locked38.6701980
12Locked38.66671025
13Locked38.6637995
14Locked38.9583967
15Locked37.6627975
16Locked38.65441007
17Locked38.9542976
18Locked38.65161016
19Locked38.64481032
20Locked37.64951037
21Locked37.6510908
22Locked38.6509926
23Locked38.9497990
24Locked37.64941014

 

Upstream bonded channels

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

1326000004.1512064 qam5
2394000004.075512064 qam4



Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0000
2ATDMA0000
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Re: Constant, frequent dropouts and packet loss

Network Log

Time Priority Description

07/07/2020 11:59:55Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:03:14criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:02:34criticalDHCP FAILED - Discover sent, no offer received;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:02:1criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:01:55criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 11:54:36criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 11:52:13Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 11:51:19criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
07/07/2020 11:49:49Warning!RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:05:5criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:04:15criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:03:43criticalReceived 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;
01/01/1970 00:02:54criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:02:27criticalReceived 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;
01/01/1970 00:01:35criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:00:31criticalTFTP Request Retries exceeded, CM unable to register
01/01/1970 00:00:31criticalTFTP failed - Request sent - No Response;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:00:30criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:00:30criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
01/01/1970 00:00:25criticalSYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
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