That’s true, I didn’t think about it that way, but what if I would just add a blueprint function, that will just call the server and ask for some answer. For example I will create function called “Check server” on client and the answer from the server would be “Hey, I am for Game XYZ”… And then everything will just continue. Any different answer would just cause that you won’t be able to login and load the game 
Something like free servers for World of Warcraft. You just had to type IP in some file to connect.