Multiplayer game godot

So, I am a okayish godot game dev and I want to bite the bullet and learn to make multiplayer games.
Im super comfortable with godot and feel very confident in making games.
but
I have no idea how anything works in networking or anything. The most complex thing I've ever done is port forwarding for minecraft and even then I followed a tutorial.

What do I need to learn before I start making multiplayer games?
Basically, I want to make Stardew Valley kind of multiplayer. Where one person can host a server and other person on same network can join.
Also, perhaps also make it so they can host servers for their friends and share it with them with "invite codes" so anyone on any network can join?

I know, This is probably super hard but. I want to start.
What is the way?

Can I just go for it by following tutorials or do I need to learn something more before I jump in?