looks like a long line issue as the upstream isn't at full rate. It's G992.1 so standard ADSL - ADSL2 might do a bit better.
Another bit of kit might do better too, I've been to places where the home hub would not sync but the 2-wire business hub or an AR7 based router did and ran at about 700k, so I would try to borrow or Ebay some alternative hardware.
I would double check there is no dial tone on any other phone when using the test socket, and ensure nothing else is hard wired into the system.
Anything below 288k sync is a fault so you could ask your ISP to get it looked at, just in case.
MaxDSL - goes as fast as it can and doesn't read the line checker first.
Are your kids pirates ? Limewire, Bearshare, Kazaa, BitTorrent, eMule are all tools of the trade.