Further thoughts, (bit off topic ?)
How do power line data connections fare with ring and possibly spurs in the same system ? Still they don't worry about crosstalk so just wind the power up ?!
This is a short explanation for people who don't know what the heck we were talking about !
If AC power splits and later recombines, more or less out of phase, the result can be loss of power maybe 30 dB in a narrow band .
For ADSL1/ADSL2+/VDSL the minimum cable distances to give this delay are of the order of 75m/37.5m/7.5m.
This sort of path difference is possible in a house if the wiring is a ring main where there are two paths, clockwise and anti-clockwise OR
with spurs where power can go direct or take the side turning only to find it is a dead end and come back delayed.
The result is attenuation of the signal at the top end of the bandwidth (IN Hz!). If the signal there is attenuated anyway due to a long cable run from exchange/cabinet, the effect won't be serious, but with a good signal it can have a marked effect.
A filtered faceplate at the master socket can be configured to block off the rest of the wiring to broadband, so eliminating the problem. This then needs dedicated cables from the router to computer(s). This is a "fair bit of work but then forget about it" solution.
WiFi is an alternative, but it can also suffer from reflected signals arriving with a delay, and in this case the corresponding distance is about 3.2 cm. There are many objects in a house capable of reflecting WiFi which may be moved this far so this is a "easy and works for the moment" solution.
