iOS 9.9.11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone 6, released on 2018-04-24T17:10:20Z. The update package is 1.46 GB. This is a delta (partial) update that requires 9.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 24f6627abbd36e710bafdcae0ed368f15b9b3d0d.zip.