Vokoun had not given up a goal for 140 minutes, 41 seconds, but he was removed from the game after two periods following the four Dallas goals on 23 shots.
Wandell, who scored five goals in 50 games last year, tallied in the final minute of each of the first two periods against the Panthers. Steve Ott and James Neal also scored for the Stars, who improved to 5-1.
Tampa Bay had allowed only five goals in its first four games, fewest in the NHL.
Kari Lehtonen was denied what would have been his first shutout in two seasons when Stephen Weiss tipped in a shot by Michael Frolik with 3:06 left in the third.
Florida stopped Dallas on its two power-play chances to remain perfect in its penalty killing this season.