1Gig Slow connection DOCSIS 3.1

[Ash_]

Hey all, IT/Software engineer here who has signed up for the 1gig package.

I was originally on the 250 MB package which as rock solid for years. Working from home more and uploading/downloading large virtual machine files required the upgrade. I took the plunge last week but the internet speed is very intermittent. 

Some days I can get 1180mbps down and 105 up and the next day it's 450mbps down and 45mb up. I have tried various connection methods including Wifi 6 enabled Macbook Pro, iPhone 14 and iPad. Additionally, I purchased a 2.5gig ethernet adaptor for my Mac thinking there might be congestion on the 2.4/5ghz range but it makes no real difference.

It's like something is going on at the exchange and it then sorts itself out a few hours later. 

I have had an engineer out who looked at everything and it was all over the place then. He replaced a few things and it was ok for a day and it's back doing the same. 

Is this normal for the 1gig connection as I am rarely seeing 1gb download and have only seen over 100mb upload two times. 

I have factory reset the router and also tried just my laptop connected but that makes no difference when it's being slow. 

Cable Modem StatusItem Status TypeChannel Overview Downstream Upstream

Cable Modem Status	Online	DOCSIS 3.0
Primary downstream channel	Locked	SC-QAM
DOCSIS 3.0 channels	31	5
DOCSIS 3.1 channels	1	1

3.0 Downstream channels

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

1	330000000	2.9	41	QAM 256	25
2	138000000	6.7	40	QAM 256	1
3	146000000	6.2	40	QAM 256	2
4	154000000	5.8	40	QAM 256	3
5	162000000	5.6	40	QAM 256	4
6	170000000	5.4	40	QAM 256	5
7	178000000	5.3	41	QAM 256	6
8	186000000	5.1	41	QAM 256	7
9	194000000	4.8	41	QAM 256	8
10	202000000	4.5	41	QAM 256	9
11	210000000	4.6	41	QAM 256	10
12	258000000	3.9	41	QAM 256	16
13	266000000	3.8	41	QAM 256	17
14	274000000	3.6	41	QAM 256	18
15	282000000	3.5	41	QAM 256	19
16	290000000	3.7	41	QAM 256	20
17	298000000	3.7	41	QAM 256	21
18	306000000	3.5	41	QAM 256	22
19	314000000	3.2	41	QAM 256	23
20	322000000	3.1	41	QAM 256	24
21	338000000	3.1	41	QAM 256	26
22	346000000	2.8	41	QAM 256	27
23	354000000	2.5	41	QAM 256	28
24	362000000	2.5	41	QAM 256	29
25	370000000	2.5	41	QAM 256	30
26	378000000	2.3	41	QAM 256	31
27	386000000	1.9	41	QAM 256	32
28	394000000	1.6	41	QAM 256	33
29	402000000	1.7	41	QAM 256	34
30	410000000	1.8	41	QAM 256	35
31	514000000	0.7	40	QAM 256	36

3.0 Downstream channels

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

1	Locked	41	9	0
2	Locked	40	0	0
3	Locked	40	2	0
4	Locked	40	0	0
5	Locked	40	0	0
6	Locked	40	0	0
7	Locked	41	2	0
8	Locked	41	1	0
9	Locked	41	0	0
10	Locked	41	0	0
11	Locked	41	0	0
12	Locked	41	0	0
13	Locked	41	1	0
14	Locked	41	2	0
15	Locked	41	2	0
16	Locked	41	1	0
17	Locked	41	3	0
18	Locked	41	3	0
19	Locked	41	1	0
20	Locked	41	7	0
21	Locked	41	4	0
22	Locked	41	4	0
23	Locked	41	4	0
24	Locked	41	8	0
25	Locked	41	4	0
26	Locked	41	9	0
27	Locked	41	6	0
28	Locked	41	5	0
29	Locked	41	3	0
30	Locked	41	6	0
31	Locked	40	10	0

3.1 Downstream channels

Channel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)

37

92

4K

1800

QAM 4096

1128

3.1 Downstream channels

Channel ID Locked Status RxMER Data (dB) PLC Power (dBmV) Corrected errors (Active Profile) Uncorrectable errors (Active Profile)

37

Locked

41

0.3

102489048

0

3.0 Upstream channels

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

0	49600000	42.5	5120	QAM 64	1
1	43100000	41.8	5120	QAM 64	2
2	36600000	40.5	5120	QAM 64	3
3	30100000	39.5	5120	QAM 64	4
4	23600000	38.5	5120	QAM 64	5

3.0 Upstream channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

0	ATDMA	0	0	0	0
1	ATDMA	0	0	0	0
2	ATDMA	0	0	0	0
3	ATDMA	0	0	0	0
4	ATDMA	0	0	0	0

3.1 Upstream channels

Channel Channel Width (MHz) Power (dBmV) FFT Type Modulation

6

10.4

38.5

2K

QAM 256

3.1 Upstream channels

Channel Channel Type Number of Active Subcarriers First Active Subcarrier (Hz) T3 Timeouts T4 Timeouts

6

OFDMA

208

74000000

0

0

General Configuration

Network accessMaximum Number of CPEsBaseline PrivacyDOCSIS ModeConfig file

Allowed

1

Enabled

3.1

cmreg-vmdg660-bbt076-b.cm

Primary Downstream Service Flow

SFIDMax Traffic RateMax Traffic BurstMin Traffic Rate

21894

1230000450 bps

42600bytes

0 bps

Primary Upstream Service Flow

SFIDMax Traffic RateMax Traffic BurstMin Traffic RateMax Concatenated BurstScheduling Type

21893

110000274 bps

42600bytes

0 bps

42600bytes

Best Effort

Any help would be much appreciated as the phone support seems to have no idea. 

[gitty]

---

@Ash_ wrote:

I have just checked my network logs again and I am now getting these errors with a bunch of critical errors;
"RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=redacted;CMTS-MAC=redacted;CM-QOS=1.1;CM-VER=3.1;"

---

Those events are not always "critical". It depends. The bigger the difference is between the upstream power levels, the more likely they will appear. Sometimes they tend to appear when you reboot the modem, depending on what the values are.

What are your upstream power levels now?

[Daniel_Et]

Hi @Ash_ 👋 Thank you for your posts and welcome to the Virgin Media Community 😀

We're sorry to hear about the problem you've been having and the poor experience you've had 😔

I can see you've been in contact with the team since your latest post. Are you any further forward with this?

Advice on how to fix slow internet speeds can be found here. 

Please pop back to us at your earliest convenience. 

Regards,
Daniel

[Ash_]

Hi Daniel,

I have an engineer booked for Tuesday to take a look at the wiring as we belive that's at fault. 

[Adduxi]

You also need to setup a BQM and let it run for a few days to gather and record your incoming circuit.    www.thinkbroadband.com/ping 

Post a link to the shared graph once it's populated as it may show you are in an oversubscribed area?

[gitty]

The size of the dynamic range window is always 12 dB. The transmit power of all the channels must be within this window, otherwise it will be a violation.

The window is divided in two (6 dB each). A top half and a bottom half. The top of the window is always at least at the same level at the channel with the highest power.

If a channel falls within the lower bottom of the window, it is said to be 6 dB below top of window. The CMTS may be able to adjust the top of the window so that is no longer true.

If there is more than 6 dB between the channels, one or more channels will always be in the bottom half.

What if the modem is commanded to violate the window...? In DOCSIS 3.0, the modem had to reject the command, but in 3.1 it must always do as the CMTS says, even if it is a violation.

[gitty]

The window (there is only one) is defined by DOCSIS to be 12 dB. Even in 4.0 it is still only 12 dB, which could be a bigger challenge, since the return path can span 5-684 MHz.

[Ashleigh_C]

Thank you for popping back and letting us know @Ash_ 

How did the visit go with the engineer?

[Ash_]

Hello.

The engineer 'Ed' was very knowledgeable and immediately saw the problem. There was excessive noise on the line apparently and he has added an attenuator to bring the upload channels within spec. 
He also left me some ducting to pass the internet cable through as we found it was just buried under the soil which was kind of him. 

It is much better, however, I have seen the odd drop in speed here and there which I can live with as the cable is 25 years old. 

[Ash_]

This evening I am getting huge drops in speeds as low as 20mbps on the upload again which is too low to accept. I have messaged Ed as he left his mobile number with the premises to update him on how I was getting on. 

I may end up dropping back to the 250mbps package as it's not working out which is a shame. 

This is a speed test sat right next to the router with 1200mbps 802.11AX connection.

[WorstISP]

Howdy Ash.

I work in networking on a larger global scale, and I have to warn you that Liberty Global are not doing well as a company. They recently moved their HQ from the UK to Bermuda, so you should take that as a giant warning.

The issues you're having are widespread throughout the UK and it's nothing to do with your local network or even your cabling. The fact is they're overprovisioning and selling bandwidth that they can't actually provide. Your best bet is to open a complaint and try to move to a new provider.

People keep saying "I went with Virgin because BT/Sky/Etc only do 65mb" but the fact is that Virgin is playing everyone for fools by selling a network they can't actually maintain.