iOS 11.4 (build 15F5079a) is an official Apple over-the-air update for the iPhone 6, released on 2018-05-17T17:02:29Z. The update package is 275.81 MB. This is a delta (partial) update that requires 11.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: ef609b7e7a550146efc147d9cdb7827a19a912cf.zip.