Room index 4 is sent as 4.04
"Also, for whatever reason, you cannot see other players when you're in the room with the index of 4. Instance syncing works fine in that room though. However, when a player in room 4 sends a P2P message containing their room index, it says they're in the room with ID 4.04 from the receiver's point of view."
Last message on 11 Apr 2015