Very easy: https://www.imore.com/how-download-tvos-11-public-beta-1-your-apple-tv
I had to restart my ATV in order for the new option (Get public beta updates) to appear.
Be careful though: it is a beta software, has bugs, and does not run as smooth as a production version.
Thanks a lot.
I will try.
I have updated my atv 4 to tvos 11 without problem.
I tried the new firmware with some 2160p hevc (h265) mkv files. No success. Stuttering is continue…
I think, ı should wait for atv 5 for 4k support.
Thanks
Works for 1080p. I guess hardware of ATV4 is not ready for 4k.
The ATV4 will be limited to 1080p HEVC. 4K HEVC will be available on the ATV5
You may just have to wait till Infuse is 100% ready for tvOS 11. Since you’re not a beta tester for Infuse you won’t be able to work with infuse betas that are being developed for better use of the betas of tvOS.
EDIT to add since James and I posted at the same time…
What James said. 
Hi James,
Is there any improvements on 24 fps support side with tvos 11 & infuse 5.5.2 ?
Do you think Apple will release a ATV5 this year?
Still some issues with some 4K 10-bit HEVC files with the iOS version for hardware based decode. See my post here:
But this wouldn’t apply to the 1080p-only A8-endowed Apple TV 4 anyway. There is no native hardware decode for HEVC on Apple TV 4.
I do. It should be relatively soon. Apple has (by accident) already listed some iTunes content as 4K HDR.
I expect a 4K Apple TV 5 release by fall.
Bloomberg states its sources have confirmed that the 4K Apple TV 5 is coming in (late) September.
The updated box, to be revealed alongside new iPhone and Apple Watch models at an event in September, will run a faster processor capable of streaming the higher-resolution 4K content, said the people, who asked not to be identified because the plans aren’t yet public. The 4K designation is a quality standard that showcases content at twice the resolution of 1080P high-definition video, meaning the clarity is often better for the viewer. Apple is also testing an updated version of its TV app, which first launched in 2016, that can aggregate programming from apps that already offer live streaming.
I haven’t tried tvOS11 yet, but just want to say a huge thanks for adding h265/HEVC support! It’s the only thing that I’ve been missing from my Apple TV, is being able to play back high bitrate 1080p HEVC videos smoothly.
I wont have to resort to h264 for much longer by the sounds of it 