iOS 11.4 (build 15F5077a) is an official Apple over-the-air update for the iPhone 6+, released on 2018-05-14T17:17:17Z. The update package is 275.93 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: 62b44d5d083db38f3f62face36e82e9cedb95545.zip.