For the fundamentals, Gaffer on Games has a series referred to as "Networked Physics" that goes over deterministic lockstep simulation in a networked (aka Multiplayer) environment, and input handling[1]. There are also other articles/series on stuff like Reliable UDP instead of TCP which is important for keeping latency low, writing a game loop with variable timestep, and other gamedev fundamentals. Gaffer on Games is a terrific resource.

The series doesn't really get in to doing things like rollback and the like, which would be "beyond fundamentals", as noted by the fact that a lot of AAA games don't even have good rollback net code.

Blizzard folks gave a GDC talk on the Overwatch architecture and their rollback implementation that is good for a conceptual discussion[2]

Here's a Gist w/ some rollback net code pseudocode that got posted in a gamedev subreddit once that I bookmarked but didn't read myself[3]

EDIT: Here's the lower-level game networking series from Gaffer as well, "Building a Game Network Protocol"[4]

[1]: https://gafferongames.com/categories/networked-physics/

[2]: https://www.youtube.com/watch?v=zrIY0eIyqmI

[3]: https://gist.github.com/rcmagic/f8d76bca32b5609e85ab156db383...

[4]: https://gafferongames.com/categories/building-a-game-network...