do you get an IP address is the first test, using these logins you can see if you are allocated an address when you aren't getting one through the correct login.
if @startup_domain works you know the line is OK
if @isp works you know you're mapped to the right ISP
what is a "connect" light ? sounds router specific to me.
You may be anle to ping a gateway and perhaps go to www.bt.net
or speedtester.bt.com but other than that the test logins go nowhere.
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.