In single matchplay, you should be able to win such game. Be sure to try to reconnect, keeping the game window open and Xing / restarting the browser in case of a freeze. When you are in the lobby and see the time count down for the opponent, just wait for this time (still 5 mins?) and then you'll be declared the winner.
I know that there are unfair players who want to alienate their opponent by disconnections and slow play - if you ignore this you should be safe.
Sometimes the game lobby won't return due to "unexpected error" or the like. This is unfortunate and may lead to unlucky losses.
If you experienced different things, please explain further.