We use an Ubuntu 14.04 server as file server in our closed network. We use apple and windows workstations (SMB protocol). Sometimes we get problems when saving files to the server like 'Could not save "file name" because write access was not granted'. This is strange since all files and folders have the login in user as owner and 755 permissions. After checking such a file it has 764 rights (rwxrw-r--) and we get this message. Sometimes after multiple safe attempts it works. I run a cronjob now every hour to reset all permissions but it's annoying.
Anyone any advice or tips?