I made a mistake by starting to build my game and then at some point tried to get the game running as an online multiplayer. I could not get this working. So I changed my strategy. First get a simple multiplayer game running on a VPS, then step by step make changes.
Dedicated Server Project Fluid Dynamics (prototype)
Building the multiplayer game on a Windows VPS and getting it to work.
Multiplayer in Blueprints
Building the lobby and menu setting for acces through Steam
Building and programming the multiplayer (replication) in C++ en BP