Connecting at too high (unstable) speed

[#1]

I am generally quite happy with the speed of my (PlusNet BBYW option 3) connection and (more importantly to me) the stability of my connection.  For several weeks, I have been permanently connected with a downstream line rate of 4736 Kbps (and my profile has been 4000).  This is perfectly acceptable to me.    However, earlier this week, there was a blip and the connection dropped.  And when I re-connected, it connected at a downstream line rate of 8096 Kbps.    This is far too high for my line - and causes the connection to drop after a short  time.  In the past, I just accepted this annoying inconvenience - and accepted that I would have to go through this palaver a few times until it settled back to a stable downstream line rate (for me this is generally around 4700-5000 Kbps).  But this time, every time I re-connect, it connects at this high rate of 8096 Kbps.  Consequently I am frequently being disconnected.  I don't mind being disconnected occasionally, but it is a big problem to me when I get disconnected so frequently - when I know if I was connected at a lower downstream line rate it would be quite OK again.  I note that my profile said 7000 yesterday and 6000 today - so maybe it is adjusting slowly, but is there any way to tell the system to stop trying to connect at such a high rate and to accept that I am happy with a downstream line rate of around 4700-5000 Kbps?    Or do I just have to accept being disconnected several times over a period of a few days before it stabilises again?

[#2]

If you raise a fault ticket, we can ask BT to increase your target SNR, which should see you reconnecting at a lower rate.
Which should do the job

[#3]

This should be added to the list of completely unexpected  complaints 

[#4]

[#5]

Another option (and assuming your router's compatible), would be to use DMT to force an SNR increase on your line. This is done at your own risk though, so if you're not au fait with ADSL technology then you may want to take James' advice instead.

[#6]

Thanks for the suggestions.  I raised a ticket this morning as suggested but nothing seems to have happened, and for the last few hours I have been disconnected several times, and nearly every time when I reconnect, it is at a downstream line rate of 8096 Kbps which is clearly too fast to be stable on my connection.  I just want to be connected at a slighty slower but (historically) much more stable rate - in my case about 5000 Kbps.    In the past when I have had to go round this loop after the odd "blip", the system would work out soon enough that it needs to go down to this level of around 5000 Kbps. At the moment it doesn't seem to be learning anything - and, for the last couple of days is just continuously connecting me at 8096 Kbps. And then I get disconnected shortly afterwards.  These interrupts are a real pain for me.

[#7]

I can understand your frustration, as I have a similar conflict with sync speeds to a lesser degree.  You may have a line or router issue, which may be fixable with a bit of investigation, but sounds like you don't need the hassle (or enjoy the challenge  :)).
One thing you may want to try, although there's the chance it may have too severe of an effect, would be to resync more than 10 times  in one hour.  This should kick the exchange into thinking your line has a problem, and automatically raise the target SNR figure.  Assuming it hasn't done so already.
Do you have any line stats to give us, eg downstream attenuation and downstream SNR margin?  Have you tried connecting to the test point at the master socket?

[#8]

My router does not disconnect at these speeds if you have an adsl 2+ router it should be able to cope
I am across the road from my exchange and get high speed downloads at 3am

puddy

[#9]

3 questions:
Is interleaving on?
What make & model of router do you have?
Is it connected at the master socket or via extension cabling?

[#10]

Many thanks for the helpful advice and suggestions from everyone.  I must say the forum has been more sympathetic / helpful than the official PlusNet ticket has been (so far anyway).  I don’t mean to sound like a moaner (and generally when the line is stable, I am perfectly happy), and I’m sorry if this sounds like a rant, but I am just a bit frustrated.

I use a BT Voyager 2100 router, and it doesn’t seem to make any difference if I use an extension socket or the master test socket.  The first response from the PlusNet ticket was that they would arrange for BT to turn interleaving on, which I found a bit strange because as far as I can see (from the ADSL line status according to the Voyager 2100 menus), I have always had interleaving turned on.  Line mode = G.dmt, Latency Type = Interleave, Line coding = trellis on.    They haven’t made any comment at all on the suggestions I told them had been made on this forum earlier by James Bailey and Bob Pullen (about raising a fault ticket so that PlusNet would ask BT to increase the target SNR, which should see me reconnecting at a lower rate). 
Things were a bit more stable yesterday as I was connected at a slightly lower downstream line rate of 6464 Kbps for a few hours – and this is (obviously) a more stable connection than 8096 or 7296.  However today it is back to 8096 and consequently, I am being disconnected again every half an hour. 
However, I am not complaining that my connection is unstable at these high rates.  I know it won’t be.
I appreciate that there are other factors (such as the distance from the BT exchange - I am about one mile away from mine).  I am not even asking for faster speeds.  I am just unhappy about being connected at unfeasibly high line rates which I know are too high for my line to cope with.    I just want to be connected at a downstream line rate of about 5000 Kbps which I know from experience is perfectly stable for my connection.
When I had a stable connection before last week, my profile was 4000 and the downstream line rate was 4736 Kbps.  This was great for me.  The line attenuation is constant at 21.0 dB.      Since last week, my profile has gone from 7000 to 6000 and yesterday and today it has been 5500.  And so I would have hoped that by now I would be getting connected at a proportionally slower speed.    However each time I reconnect now, the downstream line rates have mostly been 8096 (with noise margins of between 6 and 7), or 7296 (noise margins generally around 10 or 11).  Yesterday for a few hours it was 6464 (with noise margins around 13).  But after a few hours, I was disconnected again (as I predicted).  The faster the downstream line rate, the more unstable the connection. And I know my connection is only really stable at a speed of around 5000.
One other point which might be relevant:  I am not powering off the router each time I get disconnected, but I usually have to reconnect manually - via the BT Voyager 2100 Configuration Manager - as I am not being reconnected automatically (even after 30 minutes).  Maybe this is what is confusing BT’s re-training process?  If I wait longer will it reconnect automatically?
I appreciate that for many people, they may be more interested in speed rather than stability, but I am paying £19.99 per month for my broadband service and personally I am not happy being disconnected every 20 minutes for a few days every few weeks while BT is apparently trying to retrain my connection.
Thanks again to everyone for their helpful comments – I hope PlusNet will be able to help me with the problem ticket soon.  People I chat with are getting to know me as a PlusNet customer who has stability problems – which is unfair as I know it is probably a case of BT’s re-training process not working very well rather than PlusNet, and also if it connected at a reasonable speed for my line, it will be quite stable.

[#11]

Use this tool to increase the SNR to 150% or more - should do the trick!
http://www.kitz.co.uk/routers/DMTv8.htm
This only changes things until the router is rebooted, its only a few clicks to change it
I'm currently using it to push mine down as my line can handle 5mb but before I was syncing around 3
Good luck!

[#12]

With a line attenuation of 21dB you should easily get a full 8mbps.
(mines 21.5 and I was on rock-solid 8mbps, now 21mbps with ADSL2+)
Also with DMT you can help protect against problems by adjusting the SNRM; the one suggested is right for you and the same I with my Netgear.
The question then has to be, why are you getting these variations and what, if anything, can you do about it.
The first thing to look at is usually your own wiring and problems there are easy to identify and fix. I didn't see any answer to the question asking you to describe that.
If it's not your wiring then you move on to a "quiet line" test and see if BT have a fixable problem.
Finally I guess you start to question either your router and/or the exchange equipment (DSLAM etc.).

[#13]

ADSL2
Didnt think Plusnet were using this yet ?

[#14]

They're not. I'm not currently connected via PlusNet.