If you have an old socket, you may also have old wiring with extensions taken off a junction box before
the master socket. This was fine for phones, and for ADSL as long as properly filtered, but it is not
fine for FTTC.
If you have got such wiring make sure the installer rectifies it. My installer assured me that it didn't matter when I raised it with him and didn't fix mine: he was wrong. My initial 60Mbps quickly dropped to 12Mbps, and even 3.5Mbps for a short time. I snipped the extension (we weren't using it for anything important) and speeds recovered in DLM's good time to around 70Mbps.
Moved (with trepidation) to BT Infinity 2 for upload speed. Happy BE user for several years.