Why it takes me 10 minutes to connect to my home internet?

Hi, I am using a Motorola SBG6580 surfboard extreme wireless cable modem gateway. There this one issue that bothers me everyday. I have a laptop that I use in school and home. but what gives a headache is that every time I was trying to connect my laptop to my home internet (Charter internet), it always took almost 10-20 minutes to fully connected. what I mean FULLY is that the notification area shows the connection to the home internet, but when I open a browser(chrome), my home page doesnt open, after maybe like 5 minutes, my homepage finnally opened. but when i was trying to open other sites, its a NO, NO... I have to wait like 20 minutes, so that I can really open every site. This situation never happened to me in school or anyother places until i used this router and Charter Internet service. I am not sure if its the router's problem or the Charter's. I was so mad sometime that I need to use Internet to take care of something in a hurry... So, I was wondering if someone has a similar problem and knows how to solve this issue. I followed the simply router installation that came with the package. (means I may set up my router incorrectly). but please, if anyone knows, it will be much appreciated. Thanks.