Is there something like Plex for media where that main computer will be the one doing the work and streaming but sends it to devices throughout the house? I know Plex has a plugin but all the posts I read about it seem to indicate it's buggy. But that's essentially what I'm trying to do.
You can use xTeVe to host your m3u as live tv through plex. Kinda slow but could be a useful solution. Also, you need a PlexPass
TVheadEnd but runs on linux and it's not noob friendly.
Yes you set it up on a PC, and the other clients access IPTV or recordings through it. No idea on the VPN front, but yes, that’s probably what happens.
NextPVR is a good option for this. It’s multiple platform, with the backend able to run on Windows, Linux, MAC or Docker. There are several front end options. It’s also free.
https://nextpvr.com