At work we are trying to implement some network security, and I feel lost in the discussion. So perhaps this might be a good starting point?
I have also noticed that I learn best by doing things. For e.g., many many years ago I struggled to understand OAuth protocol, or even load balancing concepts by reading tons and tons of articles on them. A few days later my understanding would vanish into thin air. Then I had to implement this for work -- I struggled but I was not only able to re-learn it, actually put it to use but also retain the theoretical concepts very well.
So I am looking to do something similar. But I don't have the luxury to be hands on at work because the security stuff would be handled by a different team.
That's why I am looking for some tutorials that would guide me but actually make me do something in a sandbox environment.
Want multiple endpoints? VMs.
Want some routing rules? Put VMs on one bridge.
Firewalls? Iptables or whatever is the thing windows uses.
General looking at the traffic to understand what's happening? Wireshark.
There's quite a bit of content there. I'm not sure what your threshold for much time is, but don't expect to dive into more than basics in <10h.
An alternative for practical application would be just to look at what you actually use and dive deep. For example two concepts: routing tables and TCP/IP header - go to the articles on wikipedia, and go deeper into things you don't know about.