iOS 11.4 (build 15F5061d) is an official Apple over-the-air update for the iPhone 6, released on 2018-05-01T17:06:05Z. The update package is 182.34 MB. This is a delta (partial) update that requires 11.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c3f566bff3807dbf01d67525bdab6d6ef7181e9d.zip.