iOS 11.4.1 (build 15G77) is an official Apple over-the-air update for the iPhone 6s+, released on 2018-07-09T17:10:28Z. The update package is 276 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: 42257652a75329b2dad575adddd3e3eb3f616177.zip.