Playback Looping in the Middles of Pieces

This happens both on my iPhone Seven and iPad Air. I’m not too sure why, but whenever I want to listen to some music on the website, it will play fine until later into the piece. All of a sudden, the piece will restart and never finish—it will keep replaying constantly. This is irritating because I would really like to hear others’ works, and I am not always with a computer or laptop.

Any help would be appreciated. Thank you in advance to everyone who offers advice!