iPadOS 9.1 (build 13B143) is an official Apple over-the-air update for the iPad mini 4 (WiFi), released on 2015-10-21T17:15:58Z. The update package is 241.05 MB. This is a delta (partial) update that requires 9.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 51b698a177d02f9986d620a6a63ed2eaedc659c2.zip.