Reduced Downstream speeds

[#1]

I would be very surprised if it were anything to do with BT capping the speed.
Ultimately, there is something causing a very high noise margin on your line.
You say there's interference on your telephone line - raise a fault with BT or whoever your voiceline supplier is.  That's what is most likely to be causing your noise margin to be high.

[#2]

Hi James,
As you can see from the previous posts I am getting a bit confused over the Noise Margin.
Is a high Noise Margin good or bad - as from previous discussions it was alluded that the higher the Noise Margin the better.
Am I ultimately looking to get as low a Noise Margin as possible?
Brian

[#3]

Quote from: newb000

I have removed all phones from my internal lines and the only thing I have pugged into the master socket is the Router/Modem via a microfilter.

One last thing before calling your landline supplier.
Have you taken the front OFF your Master socket, just undo two screws? This reveals the Test Socket which means you are fully disconnected from your internal phone wiring. Connect to this 1st before doing anything else and try a couple of different micro-filters in the socket too.
SW.

[#4]

Brian - Ideally you want your noise margin to be around 6dB.

[#5]

James,
I have done a speed test using the BT speedtester and this shows my IP profile of 5000. Am at work so can't post actual result at the moment.
I was getting speeds of approx 12000 using this test before.
I was having problems with gettiing connections a day or so before the speed dropped - could the IP profile have been trained to a lower IP Profile - is there anything that could be done to increase that profile.
Brian.

[#6]

Brian,
Your sync speeds DROPPED because your noise margin ROSE.
A rise in noise margin is consistent with a voice fault occurring on your line, such as a level of interference.  If the interference is fixed, then I would expect your noise margin to DROP and your sync speeds to RISE.
You'll need to get in touch with whoever you pay for your line rental to report a fault.

[#7]

Hi,
I checked my line using the test point on the master socket and that made no difference. I have called BT and they did a line test and reported no problem on my line. They have arranged for an engineer to come around on Friday. I hope they find something as otherwise I will be charged.
Do I need to explain to the engineer that I am on the 21CN trial and show the Noise Margin that my router is reporting?

[#8]

Quote from: newb000

Do I need to explain to the engineer that I am on the 21CN trial and show the Noise Margin that my router is reporting?

Hi
I'm not sure I would, the engineer might put it down to just "teething" problems and leave.

[#9]

Nope, definitely not.
Just say you have a noisy line

[#10]

Hi,
The BT engineer has been and he found that there was water around the cable which he removed. The noise has now gone off my line but unfortunately my download speed and noise margin has not changed. 
ADSL Link                 Downstream     Upstream
Connection Speed     6655 kbps         1030 kbps
Line Attenuation         28.5 db             14.7 db
Noise Margin             23.1 db             6.3 db
Should I expect the changes to happen immediately or will it require something to be done at the exchange or do I need to do something (I have rebooted my router - a Netgear 834GT)
I have also done a BT speedtest and got the results attached below. Not sure where this leaves me. Any suggestions?

[#11]

If you click on https://portal.plus.net/my.html?action=data_transfer_speed
What does it say for 'Your Current Line Speed' ? This needs to read 5000 or so too.
SW.

[#12]

My "Current Line Speed" is 12000 as it was before last Wednesday when my speeds suddenly dropped.
My BT IP Profile was 12000 before last Wednesday and is now 5500. I would have expected my BT IP Profile to have gone back to 12000 now that the noise has been removed from my phone line - and I would have expected my router to have re-synced at approx 12000 too.
This hasn't happened.

[#13]

Have you rebooted?
Your noise margin is still really high.

[#14]

Hi James,
Yes I have rebooted several times.

[#15]

and every time the sync speed is the same - it is about time this was looked at