iPadOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPad mini 3 (WiFi), released on 2018-04-24T17:06:30Z. The update package is 607.86 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: f02f5341fe484f87ab3db28afe1a386ffd4993d8.zip.