iOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPhone 6+, released on 2018-03-29T17:12:18Z. The update package is 1.41 GB. This is a delta (partial) update that requires 10.3.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: e5ece1a1ed3663ffa39870626a0551e1449a46bf.zip.