iOS 9.9.11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone 6+, released on 2018-04-24T17:10:08Z. The update package is 1.77 GB. This is a delta (partial) update that requires 8.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 46f9bccf54bf48ff57c2b6c3b7b680c18c06e495.zip.