Hello~I have that happen to me many times before. Your best bet is to unplug your modem for about 1 minute and then plug it back in. Sometimes the modem needs to reset and when you unplug it/replug back in, it helps you get a clearer connection.
If this doesn't work and go to your DSL help site and follow their tips about connection issues. These help sites can diagnose any problems and fix them automatically. Good Luck...