Sorry if I confuse you, but personally, as a C++ developer, I actually started learning the C++ side of Unreal first. It’s been several years now since then and I still find UE4 C++ clearer and more understandable than Blueprints.
At first I read a few books about UE4 and they all were helpful, but there is a Udemy course that helped me the most when I was starting my adventure with UE4 - “Unreal Engine C++ Developer: Learn C++ and Make Video Games”:
This course covers a lot of ground and it’s easy to understand.
If you want to get started with UE4 - check this course, I highly recommend it!
If I remember correcty, this course was available on https://learn.unrealengine.com/ for free, however, I can’t find it there now…
As for the multiplayer functionality, I completed this course - " Unreal Engine 4 Mastery: Create Multiplayer Games with C++" by Tom Looman:
However, have a look at the first course before getting into the multiplayer one, as I think you should know the basics before diving into networking (multiplayer).
Good luck:)