iOS playback error

On my iPhone (6.5.8), nothing will play. On my Apple TV, everything plays fine.

Are these files you have downloaded to your phone or are you streaming from a local server or from a cloud server?

If streaming from a local server what protocol? SMB FTP etc?

Are you able to see the files in the shares and library on the iOS device?

All these files are in a Synology NAS and being accessed over SMB. I can see all the files on ask devices running Infuse, even when I add more, all devices get the updated file listing. It stopped working recently, maybe after I inflated iOS to version 14.3.

Kind regards,