Downstream Connection speed has been reduced from 3600 Kbps to 2400 Kbps

[#1]

It looks like the BT equipment at the exchange has raised your SNR margin to 15 in response to errors.
Not sure what, if anything you can do about that unless you can identify the reason and convince PlusNet enough to convince BT to set it back to 6.
As mentioned above, with certain routers (what is yours?) you can override this to improve speed at the risk of causing disconnections.

[#2]

@gm4jjj, you're target SNR has now been lowered to 12db.
@DarT, yours is yet to be done but I'd imagine we can get some movement on it today.
@Dan the Van, I can try getting your SNR decreased but your downstream attenuation is quite high so there's probably not a massive amount of worth in dropping it below 9-12db. Let me know if you'd like me to do this.

[#3]

Bob,
Can you drop to 12 db to start with and I will give it a go.
Please let me know when the change has been made.
Many thanks
Dan.

[#4]

Thanks Bob, Hasn't changed yet, but expect it after 12:00 today.
New Router expected tomorrow, so will see if I can keep the link stable at night.
Thanks again for your help.

[#5]

Quote from: gm4jjj

Thanks Bob, Hasn't changed yet, but expect it after 12:00 today. New Router expected tomorrow, so will see if I can keep the link stable at night. Thanks again for your help.

No problem. Let me know how you get on.

Quote from: Dan

Can you drop to 12 db to start with and I will give it a go.

Will do.

[#6]

Right, everyone's SNR changes have now been actioned. You may need to wait until after 4:00pm and give your kit a reboot for the new changes to take affect.

[#7]

Bob,
Do you have a new system for noise margin changes. It used to take forever to get BT to actually do it

[#8]

Quote from: Oldjim

Do you have a new system for noise margin changes. It used to take forever to get BT to actually do it

Yes, I like to call it gentle persuasion
On a serious note, the subject cropped up in a recent service review we had with BT Wholesale where they told us specifically what they would like us to do with these requests. We've been advised to monitor the process closely and feed back any findings so I'd imagine they'll be on their best behaviour at present.
They have stated that they will not action persistent requests though, where the SNR increases again shortly after the change.

[#9]

Bob, have you any advice to offer any direct BT Broadband customers for dealing with this issue?
A good friend of mine had a terrible speed and high SNRM (15dB) which I helped him pin down to old (antique!) phone wiring hidden unknowingly inside his originally 1920's house.
Now all sorted he's forcing a maximum 8mbps (was only 2!) by using the DMT tool and getting total stability, but would like BT to reset him to a normal 6dB SNRM so that method isn't required.
They seem totally unhelpful, though he has got interleaving turned off (excuse - heavy gaming by his sons).
Are there any magic words he could use, or is he just talking to people who won't/can't understand - obviously as a BT domestic customer he's not talking to the same people as PN do. 

[#10]

Thanks Bob,
I will leave mine as it is for the next couple of weeks to be sure that the problems are solved before asking for mine to be dropped to 12dB.
For information - any idea how many resynchs in an hour would cause the noise margin to rise. I ask because in high winds we tend to get a sequence of short duration power cuts which is what happened last time you reduced it and it went straight back up to 15dB

[#11]

HPSauce,
Ultimately, if BT Retail aren't following the recommended processes for getting SNR change requests done, there's not a lot of advice that we can offer should of recommending that he gets a MAC Code and let PlusNet sort it out for him

[#12]

Quote from: Jameseh

... gets a MAC Code and let PlusNet sort it out for him

(you never know)

[#13]

Quote from: Bob

Right, everyone's SNR changes have now been actioned. You may need to wait until after 4:00pm and give your kit a reboot for the new changes to take affect.

Thanks Bob 
Have rebooted the router and I am now back sync'd at my normal level of around 2100, with noise of around 6db.  The connection has been stable since this reboot (about 12 hours), so will monitor further.
One question I have, the sync is now back to normal, but download speed at present is around 480, and my ip profile is at 750, both still much lower than they used to be (cant remember what they were but expect ip was probably 1.5).  Am I right in assuming that these will be increased automatically by BT when I have had a period stable connection for 3 days ?  Seem to remember reading this somewhere or am i just dreaming this up. 
Thanks
DarT

[#14]

Quote from: HPsauce

Now all sorted he's forcing a maximum 8mbps (was only 2!) by using the DMT tool and getting total stability, but would like BT to reset him to a normal 6dB SNRM so that method isn't required.

When MaxDSL was introduced, there were suggestions that the SNR margin would be dropped if the connection stayed stable for 14 days without a drop.
Some say this happens. Though it has never worked for me.
SW.

[#15]

Afaik, this is meant to be 28 days.
But I'll go with what you're saying.  I've not seen it happen either.