tvOS 12.1.1 (build 16K5045a) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2018-11-29T18:09:21Z. 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: cf7033f4e7251f77a481773d64f0d1805ac6a9d3.zip.