iOS 9.3.6 (build 13G37) is an official Apple over-the-air update for the iPhone 4s, released on 2019-07-22T17:06:54Z. The update package is 256.27 MB. This is a delta (partial) update that requires 9.0.1 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: ebe200d1f74f601506e3e486b3dc83f2d2c8c5bf.zip.