I bought a new Sony tv 2 years ago that claimed it had a built in media player and could play 4k x265 content but even ath 1080p it chugged like mad and the audio was always out of sync. It just wasn't up to the task and clearly needed either better hardware or more oomph to handle the demand. I always get the impression with these things that they do the minimum so they can advertise a tonne of modern technical features the tv can do but when it comes to reality it doesn't handle them so well.
The reason why I am telling you this is because my solution is worth 100 times its weight in gold. I discussed my problem with a friend and he recommended a
Vero 4k. It is an absolute beast and plays everything and anything and I can't recommend it enough, I have got 3 in the house now connected to every tv. I would never have paid for and bought something like that at face value but I was more comfortable doing it because my friend is an IT Pro and I trust his advice. Even though it is a more costly solution I promise it is worth every single penny plus more. I use them every day and they do all the heavy lifting. The only thing the tv has to do is display the picture.