iOS 11.3 (build 15E5211a) is an official Apple over-the-air update for the iPhone 6+, released on 2018-03-12T17:05:46Z. The update package is 228.85 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: dd4c287c5fd3cc60c4330bdf45c59e7f711514ef.zip.