As I said, that just sounds like BT's DLM. It looks like your are on a 21CN line so better off than the stone age 20CN rules some of us have to put up with

I can't see how PN would be able to fix your TSNRM to 3db as they can only operate with what BT allow them?

That's what you keep saying.

There is no problem with the line. The broadband can be fast.

Those are the facts. Work out that whatever is causing it, is not me, and I have to assume that it's either my ISP, or my ISP has not one clue as to what it is. Therefore, what is the point in staying with said ISP?

See my sig link. See the speed test history. See the gradual decline of speeds. Note the batch above 13 Meg. Not an occasional thing at the time, but the norm. There's just no consistency to what I'll get now. Sometimes it's 12.5 Meg and 30 mins later it's 8 or 9 Meg.

If that's a line fault, it must be the best one yet, as I've been able to get those speeds from 2.2km from the exchange.

Edit: Not aiming that at you badger. Just letting you know I'm reading your post.

Edited by camieabz (Sat 20-Oct-12 17:29:28)

There is no problem with the line.

Wrong. RouterStats proves there is.

The broadband can be fast.

Yes. When the intermittent fault isn't occurring. So what?

I gave you stage 1 of a few diagnostic tests, and so far as I can tell you haven't done what I suggested. You do appear to have either contacted Plusnet about it, if they have indeed raised the margin to 9dB, and/or to have been under some misapprehension about the previous 3dB. As others have pointed out. There have never been any reports here of anyone having a 3dB noise margin on BT Wholesale that has not resulted purely and simply from the way the latest DLM works, except where people have tweaked it themselves. Are you sure it wasn't you forcing it to 3dB in RouterStats, and it has now been hiked so high by the DLM that 9dB is the lowest it can force?

The fact you said they had fixed it at 3dB was one of the things making me wonder about LLU, as again - agreeing with other posts - I'm not aware of any way PN can fix a noise margin at 3dB. PN certainly would not intervene to change the 3dB, (fixed or not), to 9dB without your having reported a problem.

Whilst they cannot, so far as anyone is aware, fix it at 3dB, they can request the BT Wholesale DLM to apply a "Stable" or "SuperStable" setting. One of which is presumably 9dB rather than the standard 6dB. If you didn't report a problem then it would appear to be the DLM automatically doing this, because of all those disconnections, as I forecast way back when I said I was fortunate to be on LLU so this couldn't happen to my line when I had the same problem.

Best speed test ever:



Snapshot of BQM from that day


Worst test in my collection:



Snapshot of BQM from that day


Bear in mind that there's not a massive amount of packet loss in either. You can see my pingtest line quality in my sig; dated 25th September.

All irrelevant if an intermittent fault developed yesterday. As shown in your routerstats which clearly show disconnections. Plusnet cannot cause disconnections at that frequency of occurrence. As far as I know, the only way they could cause a loss of sync would be via a broadband cease. Which clearly hasn't happened.

In reply to a post by RobertoS:

The fact you said they had fixed it at 3dB was one of the things making me wonder about LLU, as again - agreeing with other posts - I'm not aware of any way PN can fix a noise margin at 3dB. PN certainly would not intervene to change the 3dB, (fixed or not), to 9dB without your having reported a problem.

Whilst they cannot, so far as anyone is aware, fix it at 3dB, they can request the BT Wholesale DLM to apply a "Stable" or "SuperStable" setting.

Sorry Rob, but you should speak to Plusnet faults team about that. I've mentioned the 3dB thing before.

Linky 1

Linky 2

So what is it then?

Probably a developing HR or similar fault. As already suggested.

It is likely you will get rapid large oscillations in the noise margin even if you don't get disconnections, next time the fault rears its head, now that the noise margin is higher. If you do, try the QLT while it is happening and see if that cures it for a while.

Then stage 2 is, the time after that, just unplug the ADSL cable from the filter/socket and see if there is noise on the QLT. If there is, you have a voice fault which you report (as intermittent) to your line rental CP. With no mention of broadband problems.

In reply to a post by camieabz:

Try their portal. Slowest site I ever visit.

I see that too.
One would have thought that an ISP's web site would at least be quick to use.
It is after all the first thing users see.

It's not just the front page either. All pages seem very slow to load to me.

Even with FTTC connections it isn't that much better.