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line disconnecting

sg585
Dabbler
Posts: 11
Thanks: 1
Registered: 12-09-2017

line disconnecting

Hi,

 

Our ADSL line, after being very stable for a couple of weeks, has suddenly started disconnecting very frequently today since early this morning. I've lost count of the disconnections (50+), but it seems barely able to hold for more than 5-10mins at a time.

There is an open fault ticket (164520956; due to auto close in a couple of days) which I've updated. The symptoms this time are pretty much the same as from early December when it was raised, and another incident in October. By the time anyone got around to testing the line in either of these cases (5-7 days) it had pretty much stabilised. The disconnections are what is concerning me - so far downstream speed is largely unaffected though upstream is suffering. We've previously had 18Mbps down from the line though more recently 14-15Mbps.

I can't see if the line is capped/banded. Quiet line test is clear and BT speedtest didn't show anything unusual this morning. I did wonder if it might be DLM reducing line profile to 3dB as it had been stable and the line simply not being able to take it which then becomes very unstableHuh

 

Current line stats below (TP Link Archer VR900) - upstream SNRM is very high:

Upstream Downstream
Current Rate(kbps) 391 14334
Max Rate(kbps) 536 17376
SNR Margin(dB) 23.9 7.3
Line Attenuation(dB) 15.1 27
Errors(pkts) 0 5907

 

Thanks in advance for any help,

Simon

8 REPLIES
kjpetrie
Rising Star
Posts: 124
Thanks: 14
Fixes: 1
Registered: 19-12-2010

Re: line disconnecting

I'm also suffering frequent disconnections today, which I've not noticed before for months. I've had 9 disconnections since my computer was switched on at 11:30 am. One of them was a router reset because my speed this morning was 440kb/s/220kb/s and websites were loading too slowly to be usable. Many were timing out.

You are not alone.

 

Batterseacolin
Newbie
Posts: 1
Registered: 08-01-2018

Re: line disconnecting

Hello, I have suddenly noticed this too, today. The internet kept dropping (the internet light on the router) and I keep losing connection. I have not done anything unusual to have resulted in this.
Is there anything Plusnet can do?
kjpetrie
Rising Star
Posts: 124
Thanks: 14
Fixes: 1
Registered: 19-12-2010

Re: line disconnecting

Is it still bad? Mine seems to have been better today. Yesterday I had poor speed and frequent disconnections but today it has been OK. Speed is only about half what it was but still adequate for my normal use. Depending on whether it's been banded it might go back up if the service holds up long-term. I would suspect either work on the cables or REIN (see http://community.plus.net/library/broadband/broadband-faults-guide-frequent-disconnection-fault-dcn/ for details) to be responsible. The problem with REIN seems to be that, unlike radio and TV signals, there is no legal protection for Internet connections against such interference, so the only real solution to REIN is Fibre, but that's going to be a long while because it will involve digging up roads to install it.

I should add that, while it might seem a co-incidence that three of us here and other users in other threads complain about the same issue, it's unlikely to be connected unless we live in the same locality. Given PN's user base, it's not really unusual if half a dozen users experience similar problems on the same day. After all, if Christmas tree lights or flashing shop signs can cause the problem, what effect will arc welders or other heavy industrial electrical plant have? It's hardly going to be rare. In fact, the surprise is it doesn't occur more often.

 

sg585
Dabbler
Posts: 11
Thanks: 1
Registered: 12-09-2017

Re: line disconnecting

Our line has definitely stabilised after the initial 36hrs of almost constant disconnections. I counted well over 150 in that time from my logs. Speed is fine.

 

We are getting a new fibre cabinet (50m away woohoo!) so OR doing work is a possibility - nothing I have any information on or could rule out.

 

I am suspicious it is weather related. Each time it has happened it has followed heavy rain/snow - but impossible to rule out unless PN can test the line when it is happening, which would require responding in a timely manner to the fault report which doesn't seem to be happening lately (still no response to my open ticket).

As long as the line remains stable I'm content to hang on until fibre becomes available.

kjpetrie
Rising Star
Posts: 124
Thanks: 14
Fixes: 1
Registered: 19-12-2010

Re: line disconnecting

Glad your speed has stayed up. Usually it doesn't because BT/Openreach's DLM is a rather crude algorithm which usually reduces the speed to improve stability. This works well if the line is subject to a constant level of background noise, roll-off and attenuation as it finds what works well on that line and stays there. The problem comes when a line suffers periodic disruption, when it just progressively slows down to a crawl, even when that's made no difference.

BT needs a more intelligent DLM algorithm that takes into account how reliably a line was operating before it dropped and whether reducing the speed actually produced an improvement, because not all drops are speed-related. In the case of REIN, it will be random interference which means nothing for line quality in the intervals between but will cause periodic drops when the equipment responsible is in use, and that needs to be distinguished from a low-quality line incapable of handling the smaller, faster signal. If a line drops because of general poor quality it would do so within minutes, not after many hours or days of reliable operation.

According to my ddclient and router records, my line dropped this morning at about 9:30 am after being up continuously since lunch time yesterday when I accidentally reconfigured my router (I was trying to change the SSID and ran the configuration wizard) and my speed has accordingly been reduced further.

kjpetrie
Rising Star
Posts: 124
Thanks: 14
Fixes: 1
Registered: 19-12-2010

Re: line disconnecting

Glad to hear it's settled down. This is my second attempt to do so as my first post was removed. I don't know why. I didn't think I'd broken any forum rules, but it's gone anyway. I made a few technical comments about DLM, but nothing abusive or offensive.

Very strange.

Moderator's note by Dick (Strat) Post recovered from Spam filter. Sorry about that.

 

sg585
Dabbler
Posts: 11
Thanks: 1
Registered: 12-09-2017

Re: line disconnecting

Well, I spoke too soon - huge number of disconnections since about 7pm last night (mostly between 2-8am) and currently still continuing, roughly every 10-15mins or so through that whole period. Current line stats below, quiet line test still clear.

Upstream Downstream
Current Rate(kbps) 1024 14335
Max Rate(kbps) 864 17208
SNR Margin(dB) 6552 6.1
Line Attenuation(dB) 15.1 27.5
Errors(pkts) 170 0

 

It would be nice if PN could test the line? Still waiting on PN to respond to my fault ticket (164520956)...

Azagoth
Grafter
Posts: 617
Thanks: 3
Registered: 01-08-2007

Re: line disconnecting

Having similar disconnections here too.  Not as many as you, but the same thing is occurring.  After months and months of a rock stable connection the line drops and then reconnects at slower speeds.  The download is only marginally slower (9700Kbps rather than 10500Kbps) but the upload speed is half of what it usually is (600Kbps rather than 1100Kbps).

 

I did post a thread about this on Thursday, but Plusnet haven't even bothered to reply yet.  So much for the top class customer service they still advertise.