tl;dr Please point me to a true beginners reference/tutorial on networking

Gradually, patiently, persistently, over the past ten years and more, I moved from Windows and Mac to all FOSS apps and then full Linux. Doing the same with my phone. Total success. Independence and self-reliance

In short its all about control, privacy, and security, in that order. And: its a long term process that requires a commitment

I understand desktop Linux (Ubuntu/Pop!_OS) well enough to get myself out of trouble when I mess up or an update breaks

*But I have no clue about networking*, and I dont know where to start

Syncthing keeps a handful of my important directories of user-files synced quite reliably

I deleted my Google account years ago. But Im still in iCloud and iOS for all the photos. Highly recommend Fastmail incidentally

I have a small cheap Linode VPS (doing nothing right now), a Mullvad client on all my devices, Tailscale on all my devices (doing nothing because I dont understand what it can do), and a Synology NAS in the closet with the modem/router (none of which I understand)

I want to:
- host my own photos and get out of Apple

- host my own bare git repos and not rely on GitHub

- host my own BitWarden server

- host my own Tail-/Headscale (whatever the noun is)

- follow up on ideas that pop up after I comprehend networking

I can HERPaDERP install packages on client and server, and copypasta configs I dont understand. Where do I go to
*understand?*