Tanenbaum's book was the one that clicked for me, doing self-study some years ago. Even though he has presumably retired now the book is still being updated:

Tanenbaum's book was the one that clicked for me, doing self-study some years ago. Even though he has presumably retired now the book is still being updated: https://www.amazon.co.uk/Computer-Networks-Global-Andrew-Tanenbaum/dp/1292374063/ https://www.amazon.co.uk/Computer-Networks-Global-Andrew-Tan...