iOS 11.0 (build 15A372) is an official Apple over-the-air update for the iPhone 6s, released on 2017-09-12T19:10:23Z. The update package is 1.06 GB. This is a delta (partial) update that requires 10.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c3e6b41918af815ae812a53e22702c7d22fefa26.zip.