Hey,
I copied the ini file from the tutorial for the DefaultEngine. I have tried using both
[OnlineSubsystem]
DefaultPlatformService=Steam and DefaultPlatformService=Null (I thought this was what was needed for LAN).
I am running the same project from my laptop and hosting a game and joining on my computer and vice versa. They are the exact same version of the project which was how it was shown in the video.
Many Thanks