Hi mrbit,
Whenever a player is disconnected from a Match Play game (challenge or regular) both players are automatically sent to the lobby and the 5 minute countdown timer starts. The disconnected player has 5 minutes to return to the lobby to resume the game. If the player cannot return in 5 minutes it's treated as a forfeit. You are actually allowed to disconnect twice during the match and receive a 5-minute timer each time. It's not until the third disconnection (or expiration of the 5 minute timer) that a forfeit actually happens. We feel that 5 minutes per each disconnection is fair to both parties.
Unfortunately we must have this restriction otherwise you would have players disconnecting on purpose and not returning to the game any time they were down in a match.