My DLM is not working

I upgraded from ee�s 40/10 fibre to 80/20. Their �fibre plus� service went liven last Thursday (06/07/2018).
Right now, I�m in 10-day line training period. So, I should be syncing at max possible speed, and if noise margin goes too high it should dial back a bit. right? DML should be testing different speeds and setting to determine best possible speed for me. Right?

Well� DLM is not doing anything. At exactly 3 am last Thursday my sync speed went from 40/10 to 63/20. And it is syncing at the same speed since. (no change in speed: no increase, on decrease).

Noise margin hasn�t changed either. It�s been exactly 6.2(db) up and 6.3(db) down since Thursday. (this also shows the speed is not increasing or decreasing).
I live 334m meters from my fibre cabinet and about 350 to 400 meters from local exchange point. Line Attenuation is 0.0 (dB) up and 14.3 (dB) down.

I should be syncing close to 80mbps. I know my line is good, we had it installed a few a years ago (2 years ago when I had standard ADSL2 over copper, I was getting close to 22mbps to the router on this line).

does anyone know why am I syncing at 63mbps instead of close to 80mbps.

Also, my ping doubled which I think is normal as it should go back to 10ms after the training period.

Edited by deleted (Mon 09-Jul-18 22:35:44)

DLM does not work like you suggest i.e.

No 10 day period on VDSL2
DLM does not test all different speeds

The line will be open and the usual sync negotiation i.e. that minute or two between modem being turned on, booting and showing sync does the testing and determines what speed you will connect at based on some rules, which is usually a 6dB target margin. The lowering to 3, 4 or 5dB and increased speeds will happen over a number of weeks or months if you have a Huawei cabinet, and it may be a week or more if the DSLAM and DLM end up offering G.INP

In short while the DLM starts with an open range of settings, over time on some lines you may see further improvements these days and may even seen the latency lower again.

On a good line of around 350m and 14dB attenuation, which roughly correspond, you could get a max achievable of maybe 90Mbps. However, if there is a high level of noise then the achievable speed will drop off.

Going by your 6.3 dB SNR and the speed you are seeing at 63Mbps points towards a noisy local environment which may be due to factirs in your house or outside.

Similarly with upstream - a good low noise line of that length would see maybe 25Mbps and the 6.2dB SNR points to a max achievable of possibly 20.5 ... so again potentially a noise problem.

thanks for your reply,

so, there is no training/stabilisation period on G.993.2 (VDSL2)? I been seeing that all over the internet. and I contacted my ISP several times and they said I am on 10 day stabilisation period.

I am aware of Openreach lowering its noise margins to 3db. but I should still be getting much better speeds then 63mbps. To me it looks like my speed is somehow capped to 63mbps.

that 6.3 db is not SNR, it's noise margin.
my router doesn't show signal to noise ratio.


DEFECT/FAILURE INDICATION
Operation Data Upstream Downstream
Noise Margin 6.2 (dB) 6.3 (dB)
Line Attenuation 0.0 (dB) 14.3 (dB)

Actually it is the SNR Margin - I know the differences between all of them (having worked in the communications filed for 40 years. I just use the term that most people use without thinking as trying to define/describe them time and again gets tedious, much the same as reminding people it should be 6.2dB not db or Db or D, or speeds in Mbps not mbps - millibits persecond, or MBps, or mBps, or Mbs ...

Your SNR Margin at just over 6 is very close to the target and will have been negotiated at 6 before moving slightly.

Edited by MHC (Mon 09-Jul-18 23:12:35)

10 days relates to an old figure recorded against ADSL2+ lines, but many ISP keep the 10 day story as DLM is usually fairly settled by then, but it does react to changes forever, i.e. after 10 days things are not fixed

The line may be suffering lots of cross talk, or you may have less then optimal wiring in the home, or was sync and dB figures from the test socket already.

Speeds may go up if the router is super stable and left alone. They may also go down.

i don't know, that could be SNR. I did the noise test on my line and there is no noise. that makes me believe that 6dB is just the level of background noise.

The noise test is about noise in the audible range.

VDSL2 is in the 2 MHz to 17 MHz range so well outside of the range you will hear, as is much of the noise that affects it.

The standard setting for SNRM is 6dB, both up and down. It is quite common for it to end up +/- 0.2dB by the time the sync process has completed.

As has been said already, you may have a constant high level of background noise, hence a low SNR. Such noise may be external, or may be a sub-optimal setup in your home. Such things as star wiring, or the modem being close to something like the electricity meter. An always on, even on standby, PVR or satellite TV receiver?

Is your modem connected to a filtered faceplate at the master, or on a dangly filter at an extension?

These are all factors that might not affect a 40/10 connection, but have a considerable effect on an 80/20 one.