tvOS 11.4 (build 15L577) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2018-05-29T17:10:00Z. The update package is 1.04 GB. This is a delta (partial) update that requires 9.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: af79b42a862f7382cd9ea829d6a426a440590b60.zip.