How does one distinguish between server-side code and client side code? The old Quake-based games had two separate projects: one for the server and the other for the client. That doesn’t seem to be the case in UE4.
If a node is server side only, it will have a little server tower icon on the upper right side of the node. Client-only nodes I think are basically only relegated to UI stuff - pretty much everything else can/does run on the client too.
If you need something to only run on one or the other, use a “switch authority” node. There’s a good BP networking tutorial here: Blueprint Networking Tutorials - Unreal Engine
The provided link is a start. I’m guessing there’s an equivalent tag for c++ modules (?)
I believe there’s a C++ networking tutorial out there too, but I haven’t done anything with C++ networking so I couldn’t really say.