Just a few thoughts.
1. Do any of your sockets have a pair of the usual BT colour coded wires, probably White with a Blue stripe, and Blue with a White stripe, or are solid colours used throughout?
2. Do you only have one Master, with all the rest being secondary sockets?
3. When you are measuring the router stats have you ensured that nothing else is plugged into any of the sockets?
1. I saw the striped wires in the other sockets. Cannot remember it if was all sockets but in all probability it was.
2. I think so. I remember seeing other codes on the other socket which were different from the code that was earlier identified as being a master socket.
3. Just the phone. But stats with phone unplugged and router rebooted are:
System Up Time 00:01:33
ADSL Link Downstream Upstream
Connection Speed 717 kbps 970 kbps
Line Attenuation 41 db 13 db
Noise Margin 12 db 12 db