iOS 11.4 (build 15F5049c) is an official Apple over-the-air update for the iPhone 6s+, released on 2018-04-16T17:08:22Z. The update package is 219.45 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: 1ee3e97a8cef2d20de2b4cfb8294b5c9c60b45a5.zip.