Ask HN: Basic Networking Introduction Resources?

I don't have a CS degree. Am learning Docker and various cloud platforms. Need to understand networking, but don't have time for an in-depth dive (e.g. https://news.ycombinator.com/item?id=17824472) / in-depth networking is not a priority now.

Please recommend short introductions of basic concepts. I mainly need to understand ports and subnets past "it's how you connect to a machine / they are subsets of IP addresses." I do understand "the internet" in terms of DNS/backbones/etc, so I don't need that.