Return to lobby

Hello, I am making a 20-round Zone Wars to play, and I want it to return all players to the initial Lobby at the end of the 20 rounds. I already tried adding an extra round (21 rounds total), with two Round Settings Devices.

In the first one, I set it to apply to all rounds and enabled all the arena spawners and disabled all the lobby spawners. In the second Round Settings Device, I set it to be for round 21 and did the opposite: disabled the arena spawners and enabled all the lobby spawners.

I hope you all can help me, thanks.