MP4 movies

I have 6 MP4 movies on my ixpand but when I play them they stop/freeze after < 1 minute. I’ve tried all 6 and have the same issue when using my ipad

Movies work fine when the ixpand is inserted in the PC

what codec is used in the MP4 container? Also sandisk has a dedicated video palyback app called TopReel. have you tried playing the videos in that app?