Network games are complicated. Learning UE4βs implementation takes effort. I think I got a basic handle on it using C++ and some blueprints after many hours.
IMHO, using C++ for a networked, dedicated server is a requirement to have all tools you need to address what you want to do.
GameMode object live ONLY on server, never a client.
Also, you could do a custom event off GameInstance, make is server only (RPC) pass it information you want. This is what I am going to work on here in a few minutes.