Custom Media Server

So I've had a media server for a while using Plex as the software with a Terra Master as the hardware. I've become dissatisfied with both for various reasons and I'd like to make my own, but I'm also open to Plex alternatives recommendations. What I want to do is replace the Terra Master with a small frame computer running Linux rather than the Linux based Terra Master OS. When using Plex I just launch the Plex app on my roku TV and it find the Plex server in my house. But if I create my own media server I don't know that the best way of building, or getting my media server user interface on my TV. I don't want to use a keyboard/mouse connected to my servers that's simply displaying on my TV, rather, I want to be able to continue to just use a remote, preferably the Roku remote but I'm open to using a 2nd remote for the media server. Also, what the best way to build an interface? As much as I hate PHP and web development, building a PHP driven page to list my ripped movies seems like the simplest approach. If I wanted to make sure the movie streamed via UDP over TCP, I also have no idea how I would accomplish that. Any suggestions. I think I'm done with Plex, or at least I hope to be. Thanks.