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Latency and Packet Loss Spikes for Months, Are These Power Levels Normal?

StillHoping
Tuning in

Hey everyone, for the last few months we have been having very high packet loss and latency spikes (ranging from only a few seconds to a few hours at a time). For a quick example here is the connection today to OpenDNS. With average latency of around 900ms during the window (the graph is for 3 hours).

StillHoping_0-1702833025134.png

Before and after will be okay with latency of between 10 and 21ms. Local traffic is completely fine. The box is a SuperHub 3 and has been running in Modem Mode for years.

I have been trying everything and speaking to Virgin Media but as the issue is intermittent they are not interested in investigating. One final thought I have is that it might be related to power levels. I don't really know anything but I feel the T3 timeouts look a bit high. What do people think? This was also during a period of the connection working, will try and capture it during a spike next time. Also, thank you so much for any time you spent on this. It has been driving me insane.

Downstream bonded channels

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

13310000005.438256 qam25
23390000005.538256 qam26
33470000005.538256 qam27
4355000000538256 qam28
53630000005.138256 qam29
6371000000538256 qam30
73790000005.538256 qam31
83870000005.538256 qam32
93950000005.438256 qam33
104030000005.638256 qam34
114110000005.538256 qam36
124190000005.138256 qam37
134270000005.138256 qam38
144350000004.338256 qam39
154430000004.137256 qam35
164510000004.138256 qam40
174590000003.937256 qam41
184670000003.737256 qam42
194750000003.437256 qam43
204830000002.737256 qam44
214910000002.737256 qam45
224990000002.537256 qam46
235070000002.237256 qam47
245150000002.538256 qam48

Downstream bonded channels

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

1Locked38.9124
2Locked38.6183
3Locked38.6100
4Locked38.600
5Locked38.6150
6Locked38.9150
7Locked38.6100
8Locked38.670
9Locked38.660
10Locked38.950
11Locked38.650
12Locked38.600
13Locked38.650
14Locked38.610
15Locked37.350
16Locked38.660
17Locked37.680
18Locked37.680
19Locked37.650
20Locked37.650
21Locked37.640
22Locked37.6230
23Locked37.620
24Locked38.670

 

Upstream bonded channels

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

14960000049512064 qam1
23660000048.8512064 qam3
32360006848512016 qam5
43010000048.3512032 qam4
54310000048.8512064 qam2

Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0040
2ATDMA0020
3ATDMA00100
4ATDMA0030
5ATDMA0040

 

16 REPLIES 16

Restarting helps for about 2 minutes but then we are immediately back to high latency.

StillHoping_0-1704461804839.png

Edit: 5 minutes after restart latency is back to where we would expect.

StillHoping_1-1704462084508.png

StillHoping_2-1704462102925.png

 

This does make me wonder if there is a bad process running on the SuperHub 3 to cause this.

 

 

 

 

StillHoping
Tuning in

Testing over the weekend and it does look like there is something happening on the hub occasionally which causes periods of slow packet processing and/or packets drops.

It looks similar to this issue where a hub replacement solved the issue: https://community.virginmedia.com/t5/Networking-and-WiFi/Hub3-in-modem-mode-ping-spikes-and-packet-l...

 

However the good news it that whenever latency to the modem increases, it can just be restarted and it will be okay until the process on the SuperHub 3 starts again (and then it is just a reboot away from being okay). This is frustrating but at least there is a workable solution in the meantime.

Hi StillHoping, 

Thanks for keeping us posted in the Community. We're sorry to hear you're continuing to have issues. 

Taking a look at things this end, it looks as though the Networks team raised a fault in the area. This has since been resolved so can you reboot the hub and let us know if things have improved?

Many thanks, 

Kath_F
Forum Team

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Thanks for coming back to us StillHoping, I can see that there is an SNR fault logged in your area at the moment. This has been open since the 4th January and has a current estimated fix time of 12.30 on Thursday 11th January.

Kind Regards,

Steven_L

jpeg1
Alessandro Volta

The data you gave in your first post showed QAM level errors on the upstream, and many T3 errors. I'm slightly surprised that these weren't commented on. 

It would be helpful if you posted the Hub data again when the reported fault has been cleared. 

 

- jpeg1
My name is NOT Alessandro. That's just a tag Virginmedia sticks on some contributors. Please ignore it.

Hi @jpeg1 and @Steven_L,

We are still experiencing the issues after the area fault was fixed. If there is high latency to the modem (anything more than 800ms) for more than 20 minutes then we automatically restart the modem. This is very annoying but we only average a modem restart every day or so it is not awful. You can see that in action here (it takes some time to restart):

StillHoping_0-1706565941789.png

In addition there is a new problem with occasional spikes in latency to 100-200ms, which is not great but at least it is useable (even with the crazily high 16% average 3hr packet loss):

StillHoping_1-1706565993721.png

StillHoping_2-1706565998446.png

These above graphs perfectly copy latency to external services (with packet loss being lower). Restarting again fixes this most of the time (or if not a cold restart will).

 

Here are what the errors look like after 10 hours of uptime (the remaining downstream bonded channels have between 3 and 8 Pre RS errors):

StillHoping_3-1706566030222.png

StillHoping_4-1706566038487.png

 

Any more help from VM would be great. Also if there is a way of profiling the Super Hub 3 in Modem mode. Or if someone knows of a way of restarting directly over a local API call would be helpful.

 

Edit: recently found this which probably lets me further automate some of this: https://github.com/KarlJorgensen/virgin-media-hub3

Thanks for coming back to us StillHoping, we will need to send out a technician to have this looked into further. I can arrange the appointment from here but would need to confirm a few details via a private message, that I will drop over in a moment. Please look out for the private message and we can get started.
Kind Regards,
Steven_L