Hey @shotty46290, as far as I know, there is no extra module to add to the Build.cs file to use replication and networking with Unreal. Anyway, to know what is the module name that you want from any class in Unreal you can check it in the documentation. In the top of any class doc you see inside References a “Module” section, that is the name you may need to add to your Build.cs if you are missing a module.
That being said, LNK errors happen when the compiler can’t find something that it is needing, many times is a missing .cpp or .h file. Other times it is fixed by deleting your Binaries, Intermediate, Saved files, then regenerating vs project files and compiling again. I’ve gotten this error when a .cpp method is not named like the .h it is defining, or maybe you copy-pasted a function into your .cpp and the name of the class doesn’t match the one in your header. I mean in the definition it would say:
void WrongClassName::MyCopyPastedMethod() {}
Hope this helps