iPadOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPad mini 2 (Cellular), released on 2018-04-24T17:06:06Z. The update package is 577.82 MB. This is a delta (partial) update that requires 11.2.6 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5a5a533bb29b2836d692aa42e9f1d3ec7ef03498.zip.