In reply to a post by gouledw:

Thanks for clearing that up. But is it worth splashing out on that router?

Definitely! Put it this way: if the Billion 7800N doesn't solve your dropping connection problem, then its very unlikely any other router will. I suggest you buy the router from Amazon (many satisfied reviewers are using it on very long lines) and if you find its no better/worse than your current router then you can return it back to Amazon within 30 days for a full refund...obviously keep the packaging. Do post your feedback if you go for the 7800N as i'm sure it will be useful for others
http://www.amazon.co.uk/Billion-BiPAC-7800N-Broadban...

Why did they lock the target margin? Your request or theirs? Unusual for them to do so.

NOTE: ISP has control of this, though people you are talking to may not have control, hence claiming only BT Wholesale has control.

An SNR reset will do nothing for you if you have the low targets set.

Who knows if another will hold the line ...

The BT Business hub 2700HGV-C is one of the best on long lines and can hold the line down to around 0dB SNR - I have actually seen my 2700 running for quite a while with a negative SNR (< 0.0 dB).

Get a copy of Router Stats or Router Stats Lite and run that for 24 hours with samples every 30 seconds and monitor the SNR and sync speed. Then host the graphs on a suitable site and provide a link to them. From the graphs it is possible to suggest the best time to resync to get continuity of service at a good (not best) speed for the line. I played around with a line about 18 months back - the user was seeing frequent disconnects and then slow speeds ... Afterwards he was seeing a good speed ( lower than maximum) but it stayed synced for almost 30 days before we initiated a resync.

You are already exceeding expectations and many will find that a line of that length will not work at all.

You may also want to "protect" the modem by making sure there is nothing electronic or electrical close by, that it is as close to the master as possible and there is nothing electrical close to the path of the incoming 'phone wire.

Link to RouterStats http://www.vwlowen.co.uk/internet/files.htm

When you loose sync the router should reconnect automatically.
If this is due to your noise margin going too low in the middle of the night then the new sync/connection speed should be lower which will give you a slower but more stable line.

Isn't this happening for you?

I have a REIN engineer coming out this afternoon to check the line, and possibly install an RF3 filter, we have a master socket with a vDSL faceplate. And I think I will try the router on the advice. BT locked it in, someone in HLC because if the speed drops, it drops a long way

REIN engineer came today and found nothing major wrong with the line. So I think I am going to go ahead with the router, as I believe I can control the SNR on it? And will arrange another engineer after a week of testing with the Billion if the problem still persists. Im thinking if after that, the only solution will be to move to Business Grade broadband where the SNR will not drop at night.

In reply to a post by gouledw:

...the only solution will be to move to Business Grade broadband where the SNR will not drop at night.

I'm afraid it doesn't work like that! #Physics

In reply to a post by gouledw:

REIN engineer came today and found nothing major wrong with the line. So I think I am going to go ahead with the router, as I believe I can control the SNR on it? And will arrange another engineer after a week of testing with the Billion if the problem still persists. Im thinking if after that, the only solution will be to move to Business Grade broadband where the SNR will not drop at night.

Yes you can change the target SNR on the Billion 7800N:

go to http://192.168.1.254/snr.cgi
and enter one of the values below and save.

standard values are.
200 = +6dB
150 = +3dB
100 = +0dB
50 = -3dB
25 = -4.5db
1 = -5.5dB

The command does not accept negative numbers. However the command can be tricked into accepting negative numbers by entering high positive numbers.

65500 = -9dB
65480 = -9.5dB
65450 = -12dB

Beat me to it, unless by business grade then something delivered over fibre all the way to property.