The MP4 is not playing on Android due to an unsupported audio codec. Moreover, there is a possibility that the MP4 file could be corrupted. However, you can install the required codec to make the video compatible with the device, no matter the reason.
Still, due to some factors, the Android phone doesn’t support the MP4 format, so we recommend using Wondershare UniConverter to convert the MP4 video to more Android-friendly formats. You can click the Device tab and select Android under the Converter window. After the file conversion, you can quickly play the clip on the phone.