Ask HN: Projects that just made things click?

I've decided it's a good time for me to focus on some practical fundamentals that aren't discussed in too much detail in uni. I've been reading a lot about networking, doing some coding in C and Rust and tackling some low-level things like programs dealing with TCP sockets, DNS, HTTP packets, etc. It wasn't really until doing this type of thing along with self-hosting my own stuff where things at a macro-level really started to click.

Anyone else have these aha moments in their career? It makes large sections of CS become much less intimidating when you actually get down and say..

"ok here is a packet, it's just bytes over a TCP socket... with a bit of bit twiddling, I can make these standards come to life."

While I did some of these things in uni, it was all very rushed. I don't feel I had the mind for these ideas to sink in so early in my engineering career. Maybe I would have if we did some really practical, hands-on things.

Books I've loved:

- Nand2Tetris

- Unix a History & Memoir

- Rust Documentation

- Distributed Services in Go

- Beej Guide to Networking/Sockets

- Code