iOS 11.4 (build 15F5071a) is an official Apple over-the-air update for the iPhone X (Global), released on 2018-05-07T17:11:33Z. The update package is 300 MB. This is a delta (partial) update that requires 11.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a59c8c68e262c6e60e6ed87377e1d688bb06d23a.zip.