Packet Loss, High Latency and Post RS Errors

[tomsinclair]

Today (since around 2am) I have experienced a fair chunk of packet loss as well as high latency. This is having an impact on services like streaming and voice calls.

I use my VM Hub in Modem mode with my own router/network setup and have determined that the issues are deffinitely not strict to the LAN. I have run various pings from my gateway router and these see the high latency and timeouts (packet loss).

My BQM shows the impact that I have seen

Static (today): https://www.thinkbroadband.com/broadband/monitoring/quality/share/ae8628bd5a151417bb3efcec6260904537...

Live: https://www.thinkbroadband.com/broadband/monitoring/quality/share/c5501e48baeb2e03991300ccbe06bd82ce...

I have attempted multiple reboots of my router and VM Hub which hasn't made much of a difference. I have also noticed that on the VM Hub the downstream channel 1 has thousands of Post RS Errors. I don't think these have just appeared though as I have noticed these before. It's also only on channel 1 and not on any of the others.

I have checked the service status and there are no issues reported in my area so I'm not sure where to go from here!

[Robert_P]

Thanks for the update  Tom, I've had a look at the levels and they're still a little out of sync. I can see the visit for Saturday was cancelled. How are the services at the moment? If you would like me to arrange another visit let me know and I'm happy to do so.

Rob

[tomsinclair]

Hi Rob,

Yes I cancelled the engineer visit as it had settled down okay. Over the past week there wasn't noticable issues; however the channel 1 Post RS errors crept up again.

About an hour ago I completely lost connectivity and recycled both my VM Hub (modem mode) and Router and my WAN IP has completely changed. I am still seeing Post RS Errors on Channel 1 and I am seeing intermittent connectivity.

Here is a link to the new graph I have generated fort the new WAN IP - https://www.thinkbroadband.com/broadband/monitoring/quality/share/d35a3d7e1f3fd5730b8a235c7dff8c8628...

Given the Post RS Errors are still there and I'm having intermittent connectivity, it may be best to get an engineer to come and take a look?

Kr,

Tom

[tomsinclair]

Last full hub reboot (power off for 5 min) was done around 3 hours ago. Still no improvement and post RS errors are through the roof on Channel 1. Link to live BQM above and below are numbers from the hub right now:

Downstream bonded channels

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

1	411000000	6.1	40	256 qam	31
2	203000000	7.4	40	256 qam	9
3	211000000	7.3	40	256 qam	10
4	219000000	7.1	40	256 qam	11
5	227000000	7	40	256 qam	12
6	235000000	7	40	256 qam	13
7	243000000	6.6	40	256 qam	14
8	251000000	6.4	40	256 qam	15
9	259000000	6	40	256 qam	16
10	267000000	6.3	40	256 qam	17
11	275000000	6.4	40	256 qam	18
12	283000000	6.5	40	256 qam	19
13	291000000	6.5	40	256 qam	20
14	299000000	6.6	40	256 qam	21
15	307000000	6.6	40	256 qam	22
16	315000000	6.9	40	256 qam	23
17	323000000	7	40	256 qam	24
18	363000000	7.1	40	256 qam	25
19	371000000	7.1	40	256 qam	26
20	379000000	6.5	40	256 qam	27
21	387000000	6	40	256 qam	28
22	395000000	6	40	256 qam	29
23	403000000	6	40	256 qam	30
24	419000000	6.1	40	256 qam	32

Downstream bonded channels

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

1	Locked	40.3	3682	440402
2	Locked	40.9	7	0
3	Locked	40.9	5	0
4	Locked	40.3	5	0
5	Locked	40.9	5	0
6	Locked	40.9	5	0
7	Locked	40.9	5	0
8	Locked	40.3	4	0
9	Locked	40.9	0	0
10	Locked	40.9	4	0
11	Locked	40.3	5	0
12	Locked	40.9	4	0
13	Locked	40.3	5	0
14	Locked	40.3	5	0
15	Locked	40.3	6	0
16	Locked	40.3	5	0
17	Locked	40.9	0	0
18	Locked	40.3	1	0
19	Locked	40.9	8	0
20	Locked	40.3	4	0
21	Locked	40.3	6	0
22	Locked	40.9	5	0
23	Locked	40.3	0	0
24	Locked	40.9	5	0

Upstream bonded channels

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

1	39399993	48.8	5120	64 qam	4
2	32600014	47.3	5120	64 qam	5
3	46199964	48.8	5120	64 qam	3
4	53699969	48.8	5120	64 qam	2

Upstream bonded 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

[tomsinclair]

Update from this morning

I decided to do a full factory reset of my VM hub (not done for quite some time). After rebooting it went back into router mode and looked like it did some sort of software update as it rebooted a few times. I plugged in my device via ethernet for testing and the connection seemed okay. When in router mode, the VM hub picked up a new WAN IP and seemed to all be working just fine. I left it around 15m and had 0 packet loss at all. I also had 0 Pre and Post RS Errors in the log. I noticed some of the power levels were slightly different too and slightly different frequencies.

At this point I decided to give Modem mode a go again with my 3rd party router. I set the VM hub to modem mode and let it boot back up (with nothing plugged into it). I then tested by plugging my device used for testing directly into the VM hub which quickly picked up an address and was connected all okay. I then plugged in my 3rd party router and gave the VM hub one more reboot as I assume the WAN IP gets selected via DHCP based on the MAC address of the router plugged in. After it came back up, my router got an IP from the VM hub (the same one that it had switched to 24h ago) but the connection seemed good this time! All power levels, frequencies and pre/post errors were still at where they were at from the router mode (0 errors).

It's now been around another 15 minutes in modem mode with my 3rd party router and so far, so good! You can see in the BQM link i posted for the new WAN IP that it all looks normal.

I'm now wondering what caused this? Was it a cooincidence and there was work going on locally, did a factory reset of the VM hub "sort itself out", did the VM hub update fix a problem? It's hard to tell, but this is the first time since seeing these problems over a week ago that my VM hub (as of now) has 0 errors.

[tomsinclair]

Link to BQM on current WAN IP - https://www.thinkbroadband.com/broadband/monitoring/quality/share/d35a3d7e1f3fd5730b8a235c7dff8c8628...

Current VM hub figures:

Downstream bonded channels

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

1	419000000	6	40	256 qam	32
2	203000000	7.1	40	256 qam	9
3	211000000	7	40	256 qam	10
4	219000000	6.9	40	256 qam	11
5	227000000	6.9	40	256 qam	12
6	235000000	6.8	40	256 qam	13
7	243000000	6.5	40	256 qam	14
8	251000000	6.4	40	256 qam	15
9	259000000	6.3	40	256 qam	16
10	267000000	6.4	40	256 qam	17
11	275000000	6.3	40	256 qam	18
12	283000000	6.3	40	256 qam	19
13	291000000	6.3	40	256 qam	20
14	299000000	6.5	40	256 qam	21
15	307000000	6.4	40	256 qam	22
16	315000000	6.5	40	256 qam	23
17	323000000	6.8	40	256 qam	24
18	363000000	6.5	40	256 qam	25
19	371000000	6.5	40	256 qam	26
20	379000000	6.4	40	256 qam	27
21	387000000	6.1	40	256 qam	28
22	395000000	6.1	40	256 qam	29
23	403000000	6	40	256 qam	30
24	411000000	6	40	256 qam	31

Downstream bonded channels

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

1	Locked	40.3	0	0
2	Locked	40.3	3	0
3	Locked	40.3	6	0
4	Locked	40.9	6	0
5	Locked	40.3	6	0
6	Locked	40.9	5	0
7	Locked	40.9	0	0
8	Locked	40.3	0	0
9	Locked	40.9	0	0
10	Locked	40.9	5	0
11	Locked	40.9	6	0
12	Locked	40.9	4	0
13	Locked	40.9	5	0
14	Locked	40.9	5	0
15	Locked	40.3	6	0
16	Locked	40.9	5	0
17	Locked	40.9	0	0
18	Locked	40.9	0	0
19	Locked	40.3	4	0
20	Locked	40.9	5	0
21	Locked	40.3	4	0
22	Locked	40.3	6	0
23	Locked	40.3	4	0
24	Locked	40.3	123	0

Upstream bonded channels

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

1	46199986	48.5	5120	64 qam	3
2	32600029	48.5	5120	64 qam	5
3	39400017	48.5	5120	64 qam	4
4	53700007	48.5	5120	64 qam	2

Upstream bonded 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

[Sofia_B]

Thanks for the update @tomsinclair. 

From the look of the BQM, things don't look too healthy currently. I've had a look into your account to see if there's any issues on our end that could be causing this. I can see there's a short term issue currently affecting service that may cause degradation or intermittent service, this should be fixed shortly. Apologies about that 🙂 

How have things been since posting? 

Thanks, 

[tomsinclair]

Hi @Sofia_B

Thinks are still okay - not had any drop outs as such since this mornings factory reset.

I just checked the VM hub and can see that Channel 24 now has Post RS Errors (all others okay and still at 0):

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

24

Locked

40.9

8754

6355

Looking at BQM it's deffinitely far better (as mentioned no packet loss), average latency maybe 10ms higher than "normal"