latency issues

[2tw2]

We seem to be having odd steps up and down in latency today. The router data looks OK except for a high number of uncorrectables on the 3.1 downstream channel.

3.1 Downstream channels

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)

33

Locked

39

-3.9

2392175303

3368844

What is going on? Can anyone advise?

Your Shared Graph

[Steven_L]

Hey @2tw2, 
Welcome back to the community and thanks for taking the time to post.
I’m sorry to hear of the issues that you’re having with your connection at the moment, I have looked into your connection and can see an issue with your downstream power levels that would need a technician to resolve. 

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.
Regards,
Steven_L

[Steven_L]

Thanks for confirming your details via private message @2tw2, your downstream power levels are a bit on the high side on our live system. 
I have arranged the appointment, and you can track your engineer appointments online. Simply sign into My Virgin Media and you will see your appointments on your account dashboard. However, this can take up to 24 hours to be updated. 
Regards,
Steven_L

[2tw2]

If they lower the downstream power levels the 3.1 channel will go too low?

[2tw2]

Isn't this all in spec? If the 3 dB attenutaor is swapped for a 6 dB one the 3.1 channel will go too low surely

3.0 Downstream channels

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

4	163000000	8.199997	37.636276	QAM256	4
1	139000000	8.800003	38.605377	QAM256	1
2	147000000	8.400002	36.609653	QAM256	2
3	155000000	8.400002	36.386890	QAM256	3
5	171000000	7.599998	37.355988	QAM256	5
6	179000000	6.699997	37.636276	QAM256	6
7	187000000	5.800003	38.605377	QAM256	7
8	195000000	5.300003	38.983261	QAM256	8
9	203000000	5.000000	38.605377	QAM256	9
10	211000000	5.199997	38.605377	QAM256	10
11	219000000	5.300003	38.605377	QAM256	11
12	227000000	5.199997	38.983261	QAM256	12
13	235000000	5.000000	38.983261	QAM256	13
14	243000000	4.900002	38.983261	QAM256	14
15	251000000	5.500000	38.983261	QAM256	15
16	259000000	5.800003	38.983261	QAM256	16
17	267000000	5.800003	38.983261	QAM256	17
18	275000000	6.000000	38.983261	QAM256	18
19	283000000	6.199997	38.983261	QAM256	19
20	291000000	6.400002	38.983261	QAM256	20
21	299000000	5.800003	38.983261	QAM256	21
22	307000000	4.800003	38.605377	QAM256	22
23	315000000	4.300003	38.605377	QAM256	23
24	323000000	3.900002	38.983261	QAM256	24
25	331000000	3.799999	38.983261	QAM256	25
26	339000000	3.500000	38.605377	QAM256	26
27	347000000	3.200001	38.605377	QAM256	27
28	355000000	3.000000	38.605377	QAM256	28
29	363000000	2.900002	38.983261	QAM256	29
30	371000000	2.799999	38.983261	QAM256	30
31	379000000	3.099998	38.605377	QAM256	31

3.0 Downstream channels

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

4	Locked	37.636276	69	0
1	Locked	38.605377	61	0
2	Locked	36.609653	144	0
3	Locked	36.386890	139	0
5	Locked	37.355988	42	0
6	Locked	37.636276	44	0
7	Locked	38.605377	62	0
8	Locked	38.983261	56	0
9	Locked	38.605377	40	0
10	Locked	38.605377	38	0
11	Locked	38.605377	34	0
12	Locked	38.983261	35	0
13	Locked	38.983261	50	0
14	Locked	38.983261	65	0
15	Locked	38.983261	66	0
16	Locked	38.983261	39	0
17	Locked	38.983261	45	0
18	Locked	38.983261	35	0
19	Locked	38.983261	39	0
20	Locked	38.983261	53	0
21	Locked	38.983261	68	0
22	Locked	38.605377	97	0
23	Locked	38.605377	180	0
24	Locked	38.983261	287	0
25	Locked	38.983261	361	0
26	Locked	38.605377	456	0
27	Locked	38.605377	573	0
28	Locked	38.605377	725	0
29	Locked	38.983261	769	0
30	Locked	38.983261	775	0
31	Locked	38.605377	685	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

1880

QAM4096

759

3.1 Downstream channels

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)

33

Locked

39

-3.4

273805125

6809465

[legacy1 · Accepted solution]

Levels are fine the spikes in the BQM are VM doing short DoS speed tests you can ask to disable this or use modem mode 

[2tw2]

Thanks. How woudd I ask to disable these speed tests?

[pete_at_home]

Firstly, there's absolutely nothing wrong with your downstream levels.  The modem will work up to +15dBmV.   Also those Pre-RS error counts are nothing to worry about.  The Post-RS values show all bit errors are being correctly ok.

You can check if they have enabled the "Samknows" speedtest by browsing to https://samknows.com/realspeed/    If your modem is enabled it will show a page with the modem doing a Docsis speedtest internally, plus the speed from your computer to the Hub.

Simply ask them to disable SamKnows on your Cable Modem.

[2tw2]

This is what I see - not sure what an internal docsys speed test would look like...

Would I ask VM or Sam Knows to disable?

[pete_at_home]

VM needs to do it.  They have a Sam dashboard that gives them an idea of speeds across the network.

Regarding latency, what you see depends on the type of test, and what other traffic is on your internal network.   The values in various internet speedtests depend on the browser, and where on the internet the server is located.    Also it depends if your connection to the Hub is wired or wireless !!

On the samknows page, click & expand the  "show more metrics" section.     This is mine.  The high latency on LAN side is because I'm remotely connected to the modem via a VPN !!