Connected to the test socket as suggested. Old results quoted, new ones below. No errors anymore so my extension is clearly a bit dodgy! Might have to leave it connected to the master and go wireless with the xbox.
Uptime: 0 days, 1:41:07
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 1,211 / 8,133
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 19.5
Line Attenuation (Up/Down) [dB]: 13.5 / 24.0
SN Margin (Up/Down) [dB]: 7.0 / 10.5
Vendor ID (Local/Remote): TMMB / BDCM
Loss of Framing (Local/Remote): 65 / 0
Loss of Signal (Local/Remote): 20 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 101 / 0
FEC Errors (Up/Down): 0 / 588
CRC Errors (Up/Down): 0 / 0
HEC Errors (Up/Down): 0 / 0
Uptime: 0 days, 0:27:31
DSL Type: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 1,211 / 8,133
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 19.5
Line Attenuation (Up/Down) [dB]: 13.5 / 24.0
SN Margin (Up/Down) [dB]: 7.0 / 14.0
Vendor ID (Local/Remote): TMMB / BDCM
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 0 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 0 / 0
HEC Errors (Up/Down): 0 / 0