iOS 10.3.1 (build 14E304) is an official Apple over-the-air update for the iPhone 6, released on 2017-04-03T17:00:34Z. The update package is 582.21 MB. This is a delta (partial) update that requires 10.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6b1ffb6bc2710de3df375e1fc4f6c9620c686807.zip.