This seems to pop up in the Search Results and the last answer suggests that Server Travel doesn’t work with specifying and changing the GameMode.
THAT IS WRONG!
You can indeed change the GameMode via every travel when specifying
?game=<Shortcode> or the classname with module name in front.
What DennyR posted above is correct in terms of telling UE4 to change the GameMode.
The only thing that you might need to keep in mind is that if you perform a ServerTravel with “RELATIVE” mode, it will grab the data from the current URL, which is your current GameMode.
You need to make sure that you travel “ABSOLUTE”. The Console Command should do this by default, but if you travel via C++, you might need to pass in an extra “TRUE” to the ServerTravel function.
Hope that helps peeps that are encountering this in the future.
PS: The Shortcode can be specified (by now?) in your Project Settings. Go to the Maps&Modes page and expand the top most advanced menu. There you should find the
GameModeClassAliases map, where you can specify the Shortcode and select the GameMode Class for it.