Not the commenter but companies like Digital Ocean has a veritable treasure trove of material that's well put together:

- https://www.digitalocean.com/community/tutorials

- https://community.hetzner.com/tutorials

For example:

https://www.digitalocean.com/community/tutorials/ufw-essenti...

Learning how all these things fit together, when to use what, etc is much harder of course. Wisdom like that often requires time, effort and persistence.

Depends a lot on where you currently are in your knowledge about Systems administration and what kind of learning materials you prefer. For me, as someone who started learning about it from the ground up (zero prior experience as a sysadmin", and learns best from books

    "UNIX and Linux System Administration Handbook"

was the starting point back then.

I’m also interested.