On Tue, 2 Sep 2008 07:19:05 +0100, TheOldFellow wrote:

Thanks. This the most probable cause as the the unfiltered phone cable
runs quite a way near the T&E ring in the loft. The router runs with a
noise margin of just 6.4 Db, so any significant extra noise will drop
it, I guess - I'm 6 Km from the exchange.

Certainly will, get as much separation as you can between the phone line
and any mains and don't run stuff parallel. If cables must cross, cross
them at 90 degrees with as much space as possible.

Consider moving the NTE to be as close as possible to where the line hits
your house(*) and fit your ADSL modem/router there as well, Running CAT5
from it your PC or network switch. CAT5 is relatively immune to
interference.

The POTS wiring can utilise the existing loft wiring to the original NTE
position and distribution.

I already have a filtered NTE5e plate, but have not got around to doing
the rewire of the phones yet. Clearly that's the first job!

Once you have sorted the wiring try a few different filters. They are not
all created equal. I bought and ADSL Nation faceplate but it doesn't work
as well as the BT MF50 dongle type. Roughly 500kbps to 1000kbps worse on
the ADSL side and less able to maintain a good daytime sync overnight.

I probably should get some RFI ferrites too, next time I'm in Maplins.
Glad I asked.

Depends where you put them. The carriers for ADSL broadband extend to
nearly 1.2MHz, you really don't want to be attenuating those upper
frequencies any more than they already are. The filter should stop pickup
on the POTS wiring getting back into the unfiltered side and thus mucking
up the ADSL signals. But pay attention to ensuring that the POTS ring and
earth wires do not connect across the filter to the unfiltered side.

(*) In theory you have to get BT Openreach to move it but don't fit it in
the loft as BT Openreach won't go there if you have a fault. Even if the
loft is fully boarded and lit.

--
Cheers
Dave.