I might recommend starting with a project.

Something like getting pi-hole running. This would help you learn some of the networking basics. But I’d recommend reading at least enough to have a conceptual foundation about the things you don’t understand along the way (DNS, DHCP, etc).

You’ll want one of their supported OS choices to keep things simple. That means one of: fedora, debian, ubuntu, or centos. I might steer you away from centos just because its user base is a bit more linux-pro so finding specific help might be more daunting, but I don’t have much experience with it either. Maybe use a “server” variant to keep your system demand to a minimum (boot to terminal only).