What needs to be learned to understand the work of the OP and network protocols, etc.?

Question

IT education

I want to understand more how this or that system works, and I would also like to know the network component well. What do I need to learn for this and how, because I teach for myself because it's just interesting?
-Thank you for the books, and for the advice. But you won’t be able to tell which PL is more suitable for such purposes, because without practice there is no knowledge.

Answer 1

UPD:

Answer 2

Why teach? Read and try to understand. Knowledge will grow from this. It makes no sense to memorize technical details, there are specifications for this.
And on the topic: Petzold "Code", and Tanenbaum's books, as already mentioned (he has not only about networks).