we're quick off the mark in Technology :)
unfortunately if your having problems with getting dissconnected or a lot or other problems then it could be the router, or the phone line, or any off your internal telephone extensions. or a bad ADSL filter.
Filters are fairly cheap (less than �10, don't pay more) so thats not a problem to try another (or if you have another one in another socket swap them over)
internal extension wiring you can rule out by plugging the router straight into the master socket and dissconnecting everything else.
if you still are having problems then it leaves a bad phone line or a bad router. to work out which though you really need to try another router or try yours on a known good line. which isn't always an easy option for most people.