iOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPhone 6s, released on 2018-03-29T17:12:36Z. The update package is 1.34 GB. This is a delta (partial) update that requires 10.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 0462854bc85cad28b4b26237b8953d310753734d.zip.