iOS 9.9.13.4 (build 17E255) is an official Apple over-the-air update for the iPhone 6s, released on 2020-03-18T17:22:01Z. The update package is 2.74 GB. This is a full OTA update that can be applied from any compatible base version. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 16f9f144825f65c45c933548c5eef4404257f7de.zip.