iOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone 6s+, released on 2018-04-24T17:11:03Z. The update package is 32.69 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: cde1a7f884c900d007cbdbe98ef6b303be7c6066.zip.