iOS 11.4 (build 15F5071a) is an official Apple over-the-air update for the iPhone 8 Plus (GSM), released on 2018-05-07T17:11:36Z. The update package is 325.05 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: 7d0cb089ca7b6b84a45020e390b10c9a7d055feb.zip.