iOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone 6s+, released on 2017-12-13T18:13:57Z. The update package is 504.62 MB. This is a delta (partial) update that requires 11.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 0ff441bdc554c651987b7a9c530cb6cc04eb8811.zip.