I have a similar issue. I followed the steps from Blueprint Multiplayer tutorial, and using some googling I was able to package the game even. But when I click “Host game”, it tries to get to the lobby, but never does that. Displays “failed to create session” error message, and throws me back into the main menu.
I’m not trying to host and join from same PC, as I can’t even START to host the game in the first place. And if I get there ill make sure to use another pc to test connection and all. IF i get there…