This button is located on the status board/the board on your right when entering a room. When pressed it will send you to a different server of the map that you are in, but before directly sending you there you will receive a warning that consists of the message " Are you sure that you want to change servers". This button is located everywhere but private servers and public private servers?! ( I forgot what it's called lol, but yk what I mean )
#Join Other Instance Button
uneven siren
Basically, when you press it you'll change to a diffrent server of the map you are in.