unity 2D authoritative server

Hi there, does anybody know of any good learning resources for making a super basic authoritative server for unity 2D game (something simple like pong)? Most everything I have seen is for 3D FPS games. I am mostly into making 2D games but I wanna get my toes wet with making an authoritative server the right way... my goal is to learn enough to create a very simple mobile multiplayer game. Thank you!