NAS File not accessable on remote pley player


Dears, I am running plex server on windows. I am accessing it via my samsung tablet and samsung phone. My media library is partly on the NAS and partly on internal hard drives. I can access all files on internal storage but if I try accessing items on NAS file is not found, make sure file is available. The NAS does show up in Explorer and files play when opened in Internet Explorer using VLC. This error is not occuring sonstantly. Sometimes it works. ANyone any idea?