Am I just being dense?

[#1]

I've been a Plusnet customer for the past 18 months or so and, apart from a few glitches have has an ok connection.
Router usually syncs up at 2500-3300k and I get a corresponding data profile of about 2000 - 2500k
Line attenuation is about 62db and the usual noise margin is 6db ish. 
Given I live about 5k from the exchange I was happy.
Since the new year all this has changed.
Sync is currently 1152, data profile is 500 - 750K attenuation is still 62 but the router can only sync at about 12db noise margin.
I've raised a ticket (23825817) and been told to wait 3 days and it'll get better.

Is my understanding of this flawed?
If I wait 3 days then the data profile may increase to 1000k which is the max for a 1152 sync.  The sync won't increase as the router needs to reboot/manually drop and re connect for this to happen.  The sync can't increase as the target noise margin for the line is too high.
How can I get this resolved?  I keep getting told to run speed tests, which timeout and don't complete.  From my own observations I'm getting about 700K out of a 750K profile which is fine apart from I usually have a 2500k profile.
My thinking is that BT have,for some reason, set a target noise margin on my line to 12db
Any help would be appreciated.
Cheers
Richard

[#2]

Hi Richard,
It would certainly appear that your line of thinking is correct.  I would expect this to be down to a target SNR aswell.  Did you have a period of instability on your line at all?  This could potentially have caused the problem.  Have you tried rebooting your router a few times to see if it then improves the noise margin?
Sync of 3300Kbps on a 62dB line is practically unheard of, so I can understand why you would want to get it back!

[#3]

I was amazed to get 3300, more usually high 2500ish with a stable 2000k profile
I first investigated this problem on Monday, swapped the router, checked master socket etc no change.
My usual router doesn't report the noise figures so I have to check with a Netgear DG834PN which does.  This showed a sync at 1300ish with a noise margin of 12db repeatedly.  Using DMT I told it to go for a 10db (lowest possible with this tool) and it negotiated at 1920.  Subsequent reboots all get a 12db margin and the poor sync. So this seemed to point to the noise margin being higher than it needs to be.
Swapping back to my usual Netgear DGFV338 gets the same low sync, currently 1152.
Any idea how to get the exchange to let me negotiate at 6db again?
Cheers
Richard

[#4]

Hi Richard,
Target SNRs are a little different as your connection is forced to connect at 12dB, rather than it being calculated on the present noise conditions on your line.
If you raise a Broadband Speed fault, then we can ask BT to reinstate the target SNR of 6dB.  Bear in mind though that this can sometimes take time.

[#5]

I am a bit surprised you can only drop the noise margin by 2dB. With the Speedtouch I can drop it by 5dB by changing the modemoption 00 value from 58 to 08

[#6]

Gloria,
I have a ticket raised about this already (23825817). 
I keep on being asked to run the speed test before it can be raised to BT. I have tried repeatedly but it has only completed once in the past 4 days saying 850K on a 1000k connection.
Do I need to raise another one of can this one be escalated?
Any idea why the  noise margin would have been forced to 12db?
Could it be that BT don't want to set a precedent of unusually high connections to remote areas
Thanks
Richard

[#7]

Hi Richard,
It's James really.  Just a silly joke!  For a little background, have a look here.
Generally, BT would change the target SNR when there's been a period of instability caused by poor hardware or increased levels of noise on the telephone line.
I'll go and action your ticket now.

[#8]

Jim,
I suppose a little investigation of the DMT options and experimentation could get the margin lower but,
a) It doesn't survive a reboot
b) My usual VPN router doesn't support any of these commands
So I'd like to get the route cause sorted.
Cheers
Richard

[#9]

Quote from: Gloria

It's James really.

You'll always be Gloria to me
Unless the bad weather or something caused problems I don't know what has changed.  To be honest I didn't use the net much over the Christmas holidays so it was just when I was working last week I noticed it.
Thanks for your help
Richard

[#10]

Can you please replace the title with something a bit more descriptive and helpful.
When people look through the titles, they like to get some idea of the content of the posts.