‘Accessory Not Supported’ for headphones

i bought an iphone7 Plus yesterday (third party seller but still brand new) and it came with the dongle (idk if that’s its official name but the headphone jack adapter thing) and when I plug in my headphones music plays for around a minute and then stops with the message “this accessory is not supported”. what do I do? my headphones aren’t by apple but I didn’t think that’d be a problem? is there any way to fix this?