If you're open to things similar to Plex, I'd recommend Jellyfin! Plex has been making some decisions lately that aren't necessarily selfhoster friendly. A selfhosted instance of Plex still authenticates using Plex's central servers (if you're internet is out or Plex is down and you want to stream your own movies or shows, that won't work due to failed authentication). That's compared to your Jellyfin instance handling authentication locally. If you can contact your server, you can watch your media. Plex has also announced a credit skipping feature, uploading credit timing to their central servers that can be restored on complete rebuild. While they say it's anonymous, they need some way to associate you and the proper credit timings, to send that back to you.

Jellyfin is earlier days in development, and you should check to see what clients are available to see if that would work with your hardware. But Jellyfin is definitely catching up, I've been very happy with their server and applications.