Steve,
If you are only 3km from the exchange, the figures seem rather high. I'm
3.8km (as the cable goes) from the exchange and have 2meg ADSL working on a
Draytek2600VG. My figures are stable and always within .5dB of: Loop Att.
39dB, SNR Margin 24dB. However I do use a SSFP aka NTE2000 aka Master socket
faceplate filter and have kept my extensions to a min'.
>
> This house has a maze of telephone extensions in almost every room, I was
> thinking of adding one of those master socket microfilters in a
It would be worth disconnecting all your extensions, just leaving the BT
master on the incoming line and testing again. If you find that the Loop
Att. figure drops below 43dB it would be worth fitting a NTE2000 SSFP
faceplate and leaving the router at this point.
As you have pointed out you don't have newer type of master socket ie the
NTE5a with removable lower half and test socket, so you could talk to your
SP and try to get a BT Broadband engineering visit to improve you wiring as
you believe it is affecting your ability to order 2meg and the stability of
your existing 1 meg service. As you have the older type master socket you
can't easily disconnect "your" extension wiring. You can, but reconnecting
it afterwards can be a problem if you don't have the correct Krone tool.
> My router (Draytek Vigor 2600VG) reports SNR as low as 4 and as high as 8,
> and loop attenuation of 50-52 depending on the day! I know these
You do need to look into why your SNR is so low, I would lay odds on one of
the extensions causing the problems. If it is still this low with all the
extensions removed talk to your SP and get a BT Broadband Engineering visit
to look into it for you. Broadband engineers are able to test the line at
several points a long your line to see if a section is at fault, and if need
be replace or swap it out. Tea and bickies may even get you a SSFP fitted
FOC !!

.
Get your Loop loss below 43dB and you shouldn't have a problem ordering 2meg
!!
73's Phill H