You usually let SDK, rather than the client application, choose a room server, and SDK chooses a room server at random.
In Strix Unreal SDK, a room server needs to be chosen when a room is created. If you create a room using Create Node Room function rather than Create Room, SDK’s automatic room server selection works.
On the other hand, if you want to choose a room server to use by a client app’s logic, you can use Search Node function to get a list of room servers, choose an appropriate room server by the logic, connect to the room server using Connect To Room Server, and call Create Room.