In an attempt to find out if the poor SNR margin figures which I get in the evenings are because of my extension wiring or BT's fault, I tried plugging my modem/router directly into the test socket of the master socket last night. The upstream noise margin dropped way down, downstream noise margin went way up and my downstream speed dropped by about a third.
The whole exercise took about 15 minutes.
Can anyone who knows about these things throw some light on the figures? Why did my downstream speed drop? Should I get in touch with my ISP/BT or try doing something about my extension wiring?
Before - through my extension
Upstream noise margin 24dB
Upstream attenuation 23.5dB
Upstream speed 448 kbps
Downstream noise margin 6dB
Downstream attenuation 33dB
Downstream speed 5984 kbps
Directly into test socket -
Upstream noise margin 8dB
Upstream attenuation 24.0dB
Upstream speed 448 kbps
Downstream noise margin 21.5dB
Downstream attenuation 33dB
Downstream speed 3456 kbps
Plugged back in through my extension
Upstream noise margin 24dB
Upstream attenuation 23.0dB
Upstream speed 448 kbps
Downstream noise margin 7dB
Downstream attenuation 33.5dB
Downstream speed 5952 kbps