watchOS 5.1 (build 16R5568d) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-10-02T17:14:54Z. The update package is 178.92 MB. This is a delta (partial) update that requires 5.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c8bc205b5e5866df9500ad1746bcfa9e970fe6c7.zip.