Extending telephone line over cat6

[Spyda]

Howdy,

When I plug my router directly into the BT master socket it syncs at 15Mbps. If I use a cat6 cable in the walls as an extension so that the router is located under the stairs the sync speed drops to about 4Mbps. Is there something obvious that I'm missing...
The cat6 cabling is about 1 year old.

Cheers for any help/pointers,

Spyda

[toscal]

I take it you are using an ADSL router. Have you tried reversing the 2 wires going into the router. In theory it shouldn't matter which way round the 2 wires go, but I have seen on occasion that it does matter.