Here's the way I currently play the 4K content I have. I put the files on my NAS (Synology DS1812) server, and have it's DLNA host serve them via a separate folder named "4KVideo". I just keep it separate so I don't mix it all in with the storage of all my other MKV files. I then use my player on my TV (Samsung HU8550) to play off of my NAS.
Plays perfectly (as well as from a USB3 stick plugged into the TV) and never skips a beat. I'm not a huge fan of DNLA, but very effective for this application, and the player on the TV plays it very well, just don't expect to get anything more than 5.1 audio (no lossless). As I have no lossless-audio 5.1+ 4K content, not a very bid deal at this point.
Although I have no full-length movies (yet), this would work just fine for those, as long as I could live without lossless audio. Ultimately, I'll likely configure a worthy 4K HTPC, but I can at least play most of the available 4K content this way for now.