iOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone 7 Plus (Global), released on 2018-04-24T17:11:30Z. The update package is 35.5 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: c2f774e3d54f7e55f99f8d7990c8965fd2f5cfa6.zip.