So fucking confused...

Anyone have a good recommendation for an easy and fool proof (for I am a fool) way of setting up a media server that doesn't involve leaving my laptop and externals on 24/7?

I've dabbled with Plex, and it works, but I have to leave my laptop on, which I don't want to do when I'm out the house.

I've had a look at some media servers, but just getting really confused.

I want something that I can log onto on my mobile or tablet, and stream a movie from the hard-drive it's stored on in my house.

Any help, most appreciated!