iOS 11.3 (build 15E5211a) is an official Apple over-the-air update for the iPhone 6s+, released on 2018-03-12T17:05:48Z. The update package is 229.04 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: 0133a8ba0cf50b14da8b542383c3413eacc823fa.zip.