Diablo® III

I'm just curious if someone can explain to me why I am disconnected from my game but not from battlenet. If it's a problem on my end at least I know it's fixable but I just don't see how. I never lose an internet connection nor am I logged out of diablo and am able to click resume in the lobby and start a new game right away. So why do I get disconnected from the actual gameplay.

This does not happen all the time. Maybe once or twice a week.

Thanks