Apple released tvOS 11 beta 5 for Gen 4 Apple TV today and is available to registered developers and beta program members. The release is scheduled for this fall.
The public testing version will be available within the next 24 hours.
Some minor improvements have been added to tvOS 11. These include the ability to sync the home screen across multiple Apple TV via iCloud, automatic switching between light and dark modes based on local time, new multitasking modes, image enhancements, notification support, customizable sounds , languages from right to left, etc.
If you are not a developer but would like to test the tvOS 11 beta on your Apple TV, you can register for the beta testing program Apple at beta.apple.com.
Register for the beta testing program only with the same Apple ID that you use for services iCloud on your devices Apple. Then go to your Apple TV in Settings → System → Software update and enable Automatic Updates.
The software update mechanism should automatically install the latest tvOS 11 beta as soon as it becomes available. If this does not happen, you can check for updates yourself at any time.
The final fourth generation tvOS 11 Apple TV will be released this fall.