A single misconfigured thing can suck real bad as you’ve seen.
Selfhosting involves lots of things that can be misconfigured or go bad.

That’s not to scare you out of it out anything, merely to congratulate you in seeking knowledge first.

Disclaimer: I’m biased towards networks because I’m a network engineer, opinions may differ.

I would say… having at least a vague grasp of layers 1-4 of the traditional network model is a decent start.
You don’t need to understand everything, but knowing a minimum will help a lot imho.

It’s hard to point you in the right direction without knowing what you already know or not.