cancel
Showing results for 
Search instead for 
Did you mean: 

Intermittent slow speeds (~0.5Mbps) for 30s, Modem Mode, Normally 300Mbps+

XDGFX
On our wavelength

Hi all,

I've seen similar posts to this one before, but they all either end without resolution, or after a VM member starts a private chat with the OP.

I get intermittent slow speeds on my VM 350 connection. Some days this will happen every 5-10 minutes, dropping the speed down to ~0.5Mbps, before returning back to ~full speed. Some days are without issue.

This happens on wired connections as well as WiFi.

I'm using Modem Mode, the router is an EdgeRouter X. Speedtests on the ER also show the same slowdown, so I'm fairly confident it's the VM hub.

As suggested in other threads I've set up a Broadband Quality Monitor here. So far it shows nothing too unexpected.

I have been getting critical errors in the VM hub network log (note MAC addresses have been redacted):

Time	Priority	Description
05/07/2021 16:58:16	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 16:46:17	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 10:49:29	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 08:32:43	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 08:23:39	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 08:04:22	notice	LAN login Success;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 08:04:14	Warning!	LAN login FAILED : Incorrect Username / Password / ConnectionType;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
04/07/2021 12:27:28	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
04/07/2021 10:46:6	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:51:40	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:37:55	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:37:31	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:37:31	critical	Ranging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:31:6	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:30:42	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:30:42	critical	Ranging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:24:18	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:23:54	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:23:54	critical	Ranging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:17:29	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

 

Most notably No Ranging Response received and SYNC Timing Synchronization failure

Upstream and downstream bonded channels are shown below, I'm not sure if these indicate an issue but each channel looks relatively consistent at least.

 

Downstream bonded channels
Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
1	474250000	8	38	256 qam	9
2	410250000	9.6	38	256 qam	1
3	418250000	9.3	38	256 qam	2
4	426250000	8.9	40	256 qam	3
5	434250000	8.5	38	256 qam	4
6	442250000	8.3	40	256 qam	5
7	450250000	8	38	256 qam	6
8	458250000	7.9	38	256 qam	7
9	466250000	7.9	38	256 qam	8
10	482250000	8.1	38	256 qam	10
11	490250000	8	38	256 qam	11
12	498250000	7.8	38	256 qam	12
13	506250000	7.5	38	256 qam	13
14	514250000	7.5	38	256 qam	14
15	522250000	7.8	38	256 qam	15
16	530250000	7.5	38	256 qam	16
17	538250000	7	38	256 qam	17
18	546250000	6.6	38	256 qam	18
19	554250000	6.6	38	256 qam	19
20	562250000	6.8	38	256 qam	20
21	570250000	7	38	256 qam	21
22	578250000	6.6	38	256 qam	22
23	586250000	6.4	38	256 qam	23
24	594250000	6.5	38	256 qam	24


Downstream bonded channels
Channel	Locked Status	RxMER (dB)	Pre RS Errors	Post RS Errors
1	Locked	38.9	771	789
2	Locked	38.9	2346	452
3	Locked	39.3	2215	469
4	Locked	40.3	2000	522
5	Locked	38.9	2040	703
6	Locked	40.3	1805	712
7	Locked	38.9	1656	798
8	Locked	38.9	1338	875
9	Locked	38.9	991	1035
10	Locked	38.9	587	586
11	Locked	38.9	543	485
12	Locked	38.9	483	601
13	Locked	38.9	337	348
14	Locked	38.9	286	143
15	Locked	38.9	295	27
16	Locked	38.6	256	6
17	Locked	38.6	307	0
18	Locked	38.9	444	4
19	Locked	38.6	508	20
20	Locked	38.9	558	30
21	Locked	38.9	553	15
22	Locked	38.9	511	52
23	Locked	38.9	494	42
24	Locked	38.6	465	33


Upstream bonded channels
Channel	Frequency (Hz)	Power (dBmV)	Symbol Rate (ksps)	Modulation	Channel ID
1	39400000	39.2	5120	16 qam	2
2	25800024	32.5	5120	16 qam	4
3	32600380	33.2	5120	16 qam	3
4	46200000	35	5120	16 qam	1


Upstream bonded channels
Channel	Channel Type	T1 Timeouts	T2 Timeouts	T3 Timeouts	T4 Timeouts
1	ATDMA	0	0	0	0
2	ATDMA	0	0	2	0
3	ATDMA	0	0	0	0
4	ATDMA	0	0	0	0

 

Any suggestions on fixing this issue?

My Broadband Ping - VM Quality
34 REPLIES 34

Hi XDGFX, 

Thanks for your post and for coming back to us with an update on things. 

I have checked things this morning and can see the area fault has since been resolved so this is no longer affecting you. 

It looks as though there are some errors logged and the power levels need some adjusting. I would like to arrange for an engineer to come to take a look at this for you. 


I just need to confirm the address to ensure we are booking the visit on the correct account. I have sent you a private message regarding this. Just click on the little plum envelope at the top right hand side of the page to access your inbox.


Thanks,

Kath_F
Forum Team

New around here? Check out the do's and don'ts, in our Community FAQs


Hi XDGFX,

 
Thanks for coming back to via private message. 


I have booked you in for the next available appointment. We cannot confirm the appointment time slot, so to view this please sign in to My Virgin Media here: My VM Just go to My Account > Track your orders.


If the appointment is unsuitable or if anyone living at your property has tested positive for Coronavirus, has been asked to self-isolate or has flu-like symptoms then please reschedule the appointment on the same link. 


Lets us know how the appointment goes. 


Take care.

Kath_F
Forum Team

New around here? Check out the do's and don'ts, in our Community FAQs


XDGFX
On our wavelength

Hi again,

The engineer came and added an attenuator to fix the power levels. I've checked a few times and power levels seem to stay within spec. For the most part, the big slowdowns have been fixed, however there are still occasional slowdowns (recently to between 10Mbps and 100Mbps).

This test was taken today at 4pm

XDGFX@Australia:~$ speedtest-cli --no-pre-allocate 
Retrieving speedtest.net configuration...
Testing from Virgin Media (XX.XXX.XX.XXX)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by Iomart (Maidenhead) [46.22 km]: 41.517 ms
Testing download speed................................................................................
Download: 97.94 Mbit/s
Testing upload speed................................................................................................
Upload: 20.09 Mbit/s

The power levels are within spec for both upstream and downstream. The speedtest was performed on the Edgerouter, connected directly to the VM hub in modem mode.

Maybe the power levels were only part of the problem, but there is a fault elsewhere?

My Broadband Ping - VM Quality

XDGFX
On our wavelength

Also, the BQM I set up seems rather spikey - this could be another indication of issues?

Below is the current monitor for reference:

XDGFX_0-1629817495445.png

---

My Broadband Ping - VM Quality

Hi XDGFX, 

Thanks for your update and apologies that you are having continued issues. 

Taking a look at the account all is looking good. Can you please try re-running the speedtest connecting the Hub directly to the Laptop or PC? This will allow us to rule out a third party router issue. Make sure you turn the Hub off, disconnect the router and connect to the PC or Laptop before turning the hub back on.

You'll also need to ensure the network card on the OC or Laptop is 1GB and that the ethernet cable is cat 6e minimum. 

Pop back here with your results. 

Thanks,

Kath_F
Forum Team

New around here? Check out the do's and don'ts, in our Community FAQs


XDGFX
On our wavelength

Hi Kath,

I'm running the speedtests on a Ubiquity EdgeRouter X. Although this device can act like a router, it is actually just a Linux computer running Debian. I'm running commands on it directly though ssh. It is connected directly to the VM hub through a required POE injector.

If the VM hub is capable of running a speed test I am open to try that, but otherwise I'm as close to the network entrypoint as possible.

I was confused for a bit about your next statement - I assume you mean ensure it supports gigabit? 😅 The ERX does indeed support up to 1Gbps. I'm currently using cat5e cable, which should support 1000BASE-T. If there's a known issue with this protocol and VM routers I'm happy to try a higher category cable, although I've never had an issue with gigabit speeds and cat5e before.

My Broadband Ping - VM Quality

Natalie_L
Forum Team (Retired)
Forum Team (Retired)

Thank you for your reply XDGFX. 

 

We have had another check from our side to ensure that no issues have developed since our message and can confirm everything is still running within spec from here. 

 

If possible, are you able to connect a Cat 6E? 

 

Thanks 

 

Nat

XDGFX
On our wavelength

Hi Nat,

I don't have any Cat 6e available at the moment, I've switched it for Cat 7 and will see if that makes a difference.

Thanks
Callum

My Broadband Ping - VM Quality

XDGFX
On our wavelength

Nope, Cat 7 doesn't seem to have helped.

If it's any help I've been keeping an eye on my BQM, and the slowdowns seem to correspond with spikes on the graph.

3da211383ccfdaa73450a8a9c0cc4860bcc1991f.png

Latency does seem to be the biggest issue - I measure download speed at about 100mbps as mentioned, however it can often take several seconds to load any webpage during this time as it seems to be taking a long time to connect to each domain.

Any other tips I can try? Maybe the VM hub is faulty? Is it possible to perform speed tests or allow BQM pings from the VM router in modem mode, so I can further rule out other equipment?

Many thanks
Callum

My Broadband Ping - VM Quality

XDGFX
On our wavelength

An example of what I've described above; some of the thumbnails on the YouTube homepage are taking several seconds to load, even though the filesizes are tiny (kB)

firefox slow loading of images.png

My Broadband Ping - VM Quality