There are an enormous number of websites and there are some book references, but as you point out, every game is different and has different needs.Further, networking technology is constantly evolving. Practices that were ideal in the era of dialup were replaced as broadband became more common. Practices common as broadband started were replaced again as networks evolved. And different game styles lead to different networking models; a slow turn-based game where a single event crosses the wire every few seconds is radically different from a Battle Royale style game with a hundred players and potentially thousands of objects where visibility, distance, cheating potential, and other rules all come into play for what gets transmitted and what stays put.
These days games tend to rely heavily on existing libraries rather than writing raw socket code themselves, so brush up on those.
If you're using an engine like Unreal or Unity or tools like GameMaker:Studio or GameSalad or similar, they all have networking components built in you should learn about. You might need to learn the underlying technologies as well if you're involved in network programming long term, but in the short term learning how your current game engine does things is generally enough.
