Audio drops from videos when playing USB 3.0 iXpand drive on iPhone 7 and on iPad Air 2

you would need to download a video converter application and use a computer to covert the video. I have used Any Video Converter in the past and it has worked well. it used to be free but I have not used it in quite a while. just run the video through the app and convert to MP4 and it should reencode the file which may solve your issue.