Slow internet speeds following a problem with phone line

ISP: Plusnet

Router: Netgear N300 Wireless Dual Band ADSL2+ Modem Router (BRAND NEW)
2 x BRAND NEW Belkin Filters
Router is currently plugged into test socket

Router Stats:
ADSL Link Downstream Upstream
Connection Speed 3776 kbps 448 kbps
Line Attenuation 47.0 db 29.5 db
Noise Margin 17.6 db 17.0 db

BT Wholesale:Your exchange is ADSL enabled, and our initial test on your line indicates that your line should be able to have an ADSL broadband service that provides a fixed line speed up to 2Mbps.
Our test also indicates that your line currently supports an estimated ADSL Max broadband line speed of 3.5Mbps; typically the line speed would range between 2.5Mbps and 4.5Mbps.

Issue:
Last Thursday morning (25/08/2011) I noticed a problem with our Internet Connection speeds, the internet had virtually dropped out altogether. I spent a few hours trying to resolve the issue by rebooting the router etc., swapping filters. I was using a fairly new TP-Link router and older filters. I eventually decided to phone Plusnet and noticed there was a problem with the telephone line, we had what seemed to be a crossed line with a dial tone as well as my connection to Plusnet, and at other times it was a "the number you have dialled is unobtainable" and the Plusnet hold messages. I tried plugging the phone direct into the test socket and it sounded like a fax machine in the background then. Plusnet raised a ticket but didn't seem to be moving very fast with it so in the end I phoned my brother who used to be a BT engineer and he confirmed I had done everything right and that it would be a problem with the line itself and not something my end. I then phoned Plusnet back on Friday morning to tell them that my brother said it was cross talk(?) and they phoned back within an hour to say it had been a problem at the exchange and was now fixed.

The phone line definitely sounds clearer and the internet has come back but it is painfully slow. Knowing that we will get charged if it is proved to be a router or filter problem, I decided to buy a new Netgear router (the one detailed above) and Belkin filters, but the problem with the very slow connection remains. I understand that the speed will have slowed down because of the unstable connection caused by the faulty phone line, but would it have really slowed down as much as it has? My husband is useless with computers and I have two sons both chomping at the bit to get back on their XBox live as the holidays are nearly over, but if we have too many things trying to access the internet then we just lose the connection completely, it's like dial-up speeds. I needed to download a driver earlier and had to hard-wire connect the laptop it was for to the router, because it was an ethernet driver required. Downloading that took about 50 minutes and we lost connection completely on the other two laptops while that was downloading. I've tried unplugging lots of things in the house, Wii chargers, Sky TV, Cordless Phones, Microwave, etc. but nothing changes. Using MyBroadbandSpeed checker recommended by Plusnet I am getting these kind of results: -

Today 00:49 113 kbps (14.1kB/s) 52 kbps (6.5kB/s)
Yesterday 23:42 138 kbps (17.3kB/s) 46 kbps (5.75kB/s)
Yesterday 21:24 135 kbps (16.9kB/s) 43 kbps (5.38kB/s)

The last person I spoke to at Plusnet got me to write down the Downstream connection speed figure before we connected the router directly to the test socket and it was 3360, moving it to the test socket it changed to 3776. He said to me before I moved it that he expected this to make a big difference and if it did then it meant the problem was in the house, something electrical interfering with it. He told me that this figure used to be 5-6k before we had these problems with the connection dropping.

My instincts are telling me that this is a problem their end but they are still running tests. If I had left the phone problem and not pushed them then it would not have been resolved as quickly as it was, and I am wondering whether I should be pushing them more or just be patient. I have some deadlines to meet for work and was planning to catch up at home over the next couple of days and I am in a bit of a mess to be honest with you. If anyone can shed any light on what they think might be happening here I would really appreciate it.

Thank you
Karen

Have just realised I should post a link to this in the Plusnet forum, can't see how to delete it and move it, sorry for confusion.

In reply to a post by pinklion:

He said to me before I moved it that he expected this to make a big difference and if it did then it meant the problem was in the house, something electrical interfering with it. He told me that this figure used to be 5-6k before we had these problems with the connection dropping.

I assume you mean 5-6Mb? He may have overlooked the fact that your SNR margin is currently around 15db, which means the BT DLM has kicked in and increased it for stability.

This is likely to have happened during the problems with your phone line. Contact Plusnet, point this out to them. This can be reset and your line sync should return to your expected rates.

Matt

I mean 5000 - 6000 as opposed to the 3360 downstream connection speed. Thank you, I will mention this other point.

OK; two problems, both of which should automatically fix themselves.

Problem 1:
Your current speeds are most likely due to the line issues you did have.
BT's "systems" will select an 'IP profile' which closely matches the lowest connection speed you've recently suffered.
If you do a speedtest using http://speedtester.bt.com/ the result will come back with your current IP profile (I suspect it'll be 135kbps).
Now your speed has recovered the "system" should respond to this and bring your profile back up (probably to around 3000kbps).
Unfortunately this can take up to several days (maybe five at most).
For large steps; it is supposed to happen almost immediately, although sometimes this doesn't happen.
Plusnet should be able to ask BT Wholesale to reset the IP profile on the line and BT should do this (in italics because many ISP staff won't understand what you're asking, and BT are notoriously awkward).

Problem 2:
As Matt has said, your 'target margin' has now gone up to 15dB (due to the line instability you had).
Unfortunately (and even though this was due to a line fault) there seems to be no mechanism (at BT) to automatically reset the target (back to the default 6dB) when BT fix line faults. They prefer to rely on their automated "systems".
The automated "system" (DLM) should, over time, drop the margin back down (bringing your speed back to its original 5Mbps).
Unfortunately; it often doesn't (I've seen plenty of perfectly good lines, one of which now connects at 12Mbps with O2, where BT's DLM had decided the line was so poor only a fixed 15dB margin was suitable) - basically it gets stuck.
Even when it does come down, it does so in 3dB steps, and seems to take forever.
Once it's back down (if it ever gets there) it seems to remain fidgety, and often goes back up at the first sign of a router re-sync/reboot.

Both of these problems can be resolved by your ISP.
They can ask for the IP profile to be reset and for the target margin to be set back to 6dB.
The problem appears to be many ISP staff are poorly trained (especially the ones on 1st line phone support - who just rely on scripts written by someone else) and if you don't word your request in precisely the right way, they get all confused and keep saying things like "you get what you get, if you're getting 135kbps, that's all your line will do".
The second problem seems to be the way the ISP reports the fault to BT. Either BT have equally poorly trained staff or just refuse to do stuff if exactly the right fault code or request isn't used.

I got so fed up with BT's stupid IP profiles on my line, I left the BT system entirely and went to BE unlimited (as they don't have the IP profile system - your speed is around 85% of the connection speed, no matter what the recent history is. They also don't have DLM which, on BT, mucks about with the target margin - affecting connection speed - and is notoriously over-sensitive).

Hopefully one of the Plusnet staff will see this post and know exactly what to do.
Other ISPs (particularly AAISP) could fix your problem in a very short time (and migrating away from Plusnet may be your only option if Plusnet can't/won't fix the problem).

Following on from the others, the thing to ask for is an "SNR reset".

I have a nasty feeling the latest way of doing that may not be available on your connection, (not ADSL2+), but Plusnet are still able to get it done. Just not as easily.

I've just phoned them and they said if they request an SNR reset now then it could make the line seem unstable again and make the problem worse. They said it is better to wait and see. They said if they request one now then it probably wouldn't get done until next week anyway. Grrrrr... I will definitely be looking into BE Unlimited if this doesn't get resolved soon. I wouldn't mind if it had been caused by faulty equipment my end but when it was due to a fault at the exchange then it is highly annoying that they can't sort this out quicker. In this age of technology it seems a ridiculous set-up. Ah well. Thanks for your help, I don't feel quite so bogged down and on my own with it at least! There's nothing worse than no internet and four unhappy faces staring at you waiting for you to sort it out!

The speed seems to have suddenly jumped on my connection and it is working much better than it has been. Hopefully this means things are on the way back to normal, phew! Thanks for your help, I've learnt a lot about how Broadband works over these past few days, it's scary how much we rely on the internet now as well.