webwat: You still havent told us what sync rate you are getting.... if it s a bit low then the top tones won't be used because they have the highest attenuation. Lower tones have the highest crosstalk, so there might be settings that limit different tones as part of the Chorus spectrum management.

5m slack is not huge; you won't even notice a change in sync rate on a 1km or 2km line. Ancient thin copper to the exchange? If theres still any around then yes it certainly has an effect but the drop cable won't make any difference to that. But if you mess with Telecom's drop cable then you become liable for it. Cat5e isn't tough enough to use as a drop cable.

just under 15 megabit sync, single jackpoint, 550 metres from cabinet, on same side of rd, and same road as cabinet.  closest side street is 650 metres further up the road.

it may or may not be coming up the road and back again.  The top tones do indeed have less signal, 28db versus 50db.  but there's a few tones with 0db.  The lowest is tone 40 with 22db.  i think multiple by 4.3 to get khz.

15Mbps with no transmission errors? So no problem then, all working as it should.