I've been dabbling with selfhosting for a bit now (home assistant and nextcloud), but it's clear that I lack a fundamental understanding of networking. For example:

• I've got OpenWRT on my router, but no idea what I'm doing when it comes to firewall settings, DNS, DHCP, etc.
• I've got a domain thru Porkbun, but no idea how to properly setup my DNS settings there to route to my local machine.
• I've got NGINX running in a docker container in a VM and can get to the UI on my local network, but no idea what I'm doing wrong with my attempts at a reverse proxy.

Does anyone here have links to a good in-depth tutorial series for learning about securely selfhosting?