watchOS 5.1.1 (build 16R6600) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-11-05T18:06:03Z. The update package is 434.12 MB. This is a delta (partial) update that requires 5.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f19f44eff4325b748e4fff508903f92d85be16fc.zip.