GTrusted

4K seems to be appearing everywhere including your smartphone.  Most smartphones can't record at the same 4K @60Hz resolution that you get when playing 4K over HDMI 2.0 from a 4K source like the Sony Ultra HD Media Player.  You at most get 4K @30Hz from phones like the iPhone 6S and Sony Xperia Z4.

So how do you play 4K video from your phone?  While the iPhone 6S only outputs 1080p, Android phones like the Xperia Z3+, Z4 and Z5 support  MHL 3.0 which can support 4K @30Hz output directly to a TV or monitor supporting MHL.

Showing the Xperia's Android user interface and photos over MHL to the Samsung TV works fine.  You can also play your songs over MHL.

Unfortunately, the Sony Xperia has a lot of problems playing any video over MHL to the Samsung Smart LED TV.  As soon as you play any video, no video will show up on either the phone or TV.  So much for MHL interoperability between Sony and Samsung.

If you want to play 4K MHL video out of your Sony Xperia, you will need to use Sony's own Bravia 4K TV.

If you want to stick with the Samsung Smart LED TV, the only option is to use Miracast based wireless display from your Xperia but the user experience isn't that great for video.