tvOS 11.3 (build 15L5186e) is an official Apple over-the-air update for the Apple TV 4K, released on 2018-02-21T18:28:52Z. The update package is 1.37 GB. This is a full OTA update that can be applied from any compatible base version. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c86503f5b9495e762d019bf7b2710654e4d1c5ca.zip.