The best way to be sure is what I said .

Assuming you are in the UK then with most ISPs DLM has been present for many years. Sky and TalkTalk being the main exceptions, with the other one being if you were on a fixed downstream speed 512kbps or 1Mbps or 2Mbps circuit.

If you disconnect and reconnect - rebooting your modem or modem/router is simplest and safest, then read the stats immediately and see if the downstream SNR(M) is within one or two tenths of 3dB or 6dB, then we can we more sure of what is happening. Post the stats again if you do that .

In reply to a post by WWWombat:

I'm pretty sure that BT's DLM is their own invention, and not available anywhere else, inside or outside the UK.

I've seen it outside of the UK.

Telstra in Australia certainly do it but like TTB/Vodafone, allow you to turn it off.

Matt

Thank you very much to all of you, you've been a great help.

Covering several posts...

I am in the UK, but don't know where you are all based......I have a curious mind and wanted to know more about DLM, not heard of it until recently.

I am with TalkTalk. They've offered to send one of their technicians (non BT) to my home if I am still concerned.

As mentioned earlier there were long term stability issues on this line once, but not since BT changed the aluminium cable to copper, which was some time ago. Now when I look at my router summary screen and see that the Modem ADSL (Sync) uptime has renewed, I don't know if it's because the connection has dropped during the night or the profile has been changed.

"As Zarjaz says, it will only move to 3dB on a very stable line, if it detects instability over a certain limit it will then revert to 6dB anyway. As I commented before, your uptime is high and very few errors suggesting a stable line."

Seems I don't have anything to worry about, which is what I need to know.

Stats after rebooting, had to log in again so couldn't see them immediately I'm afraid (tried twice):


ADSL (Sync) Summary
System uptime: 0:01:56
Modem ADSL (Sync) uptime: 0:00:50
Interleaving: On
ADSL mode: ADSL2+
ADSL settings: PVC:0/38
ADSL line speed (kbps): up 1139 down 9214
Line attentuation (dB): up 23.8 down 43.0
SN margin (dB): up 6.2 down 3.7
Total errors seconds: 0

I am with TalkTalk. They've offered to send one of their technicians (non BT) to my home if I am still concerned.

One of their 'Bright Spark engineers' .... a chocolate tea pot springs to mind.

Interesting figures there, but what is noticeable is that it is nothing to do with overnight. There was a power down and up to the internal electronics (not a mains power off) 1 minute 56 seconds before you took the stats. That was the reboot which reset the uptime and of course the sync time. It took 1 minute 6 seconds from the reboot for it to sync with the exchange. (The second and third lines).

The margin at 3.7dB looks to be some strange setting - possibly 4dB at the moment it sync'ed. Your sync itself has not significantly changed.

You said at the start you had just been moved onto DLM (Dynamic Line Management). Did TalkTalk tell you that? If so, they have changed their system. They used not to have a DLM. Basically for that reason everything we have all said earlier about detail is to do with the BT Wholesale DLM - unless I'm mistaken none of us knew TT now have one. Sky probably still doesn't. In broader terms, you've been given some links to the general principles of DLM, which of course are still valid.

I don't think you have anything to worry about. If you see it below, say, 1dB, then it might get dodgy. It is supposed to hold sync to 0dB and some modems/routers will even hold to -1dB. I know that sounds impossible, but all a negative means is that the estimate your modem made at the time iy sync'ed was a bit out. Like opinion polls!

Edited by RobertoS (Thu 24-Nov-16 20:19:41)

unless I'm mistaken none of us knew TT now have one.

NAFAIK either.

There's a notice on the TT Community page that says they are moving over to DLM but it doesn't give a timescale.

The exact text is 'Did you know - We are moving to a new DLM system, this means that in the future OCE's will not be able to select individual profiles anymore'

I do wonder how they can manage up to 4million routers manually (number taken from current subscriber info, could be way out but still millions).

I believe the OP has a HG533 router as the stats are presented in exactly the same way as mine.

In reply to a post by RobertoS:

Sky probably still doesn't.

Sky have been using Assia's kit since 2008
http://www.ispreview.co.uk/news/EkkuEVAAyFuhUufScx.html

In reply to a post by EloiseJane:

I am in the UK, but don't know where you are all based......I have a curious mind and wanted to know more about DLM, not heard of it until recently.

Almost everyone here is in the UK too.

Really appreciate you looking at that RobertoS.

I rebooted through my computer Summary Screen without touching the router.....it said it would take around 2 minutes.

For a while both up and down SN margins were around 6 after the changeover to DLM.

I'll try a reboot again tomorrow.

Yes, TalkTalk did tell me that; I was offered a new package at a lower price. >>>

"I'm sorry we can't manually override DLM, the profile is set by an automated process, DLM monitors connection stability and errors and sets a line profile to give a fast speed with stable connection and low error count."

Yes, a Bright Spark engineer. Have to say though that TalkTalk have helped me a lot since I joined. I go straight to the top.

Oh ok that's good, almost everyone here in the UK.