iOS 11.4 (build 15F79) is an official Apple over-the-air update for the iPhone 6s, released on 2018-05-29T17:16:29Z. The update package is 733.24 MB. This is a delta (partial) update that requires 11.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f045df1a54d6257c6e533442d46de5747e35934f.zip.