Welcome to AudoCircle.
First off your chmod -R might not work if the numerical values of the user id doesn't match that of the mpd server, so really not the right approach. Also I think you need to have 'auto' or 'defaults' in the options for mount -a to automatically mount it. NFS configured incorrectly can be a security nightmare. I would actually avoid using NFS especially if you are new to linux and steer you to just using SAMBA (aka smb or cifs) since it works very well with windows, macs and linux without much effort. If you've enabled SMB on your NAS and can mount the drive with your windows or mac machine then you can update the fstab with the following:
#SMB/CIFS flavor that will mount the NAS volume as user and group "mpd" and is read-write.Where:
//MUZIEKNAS.LOCAL/volume1/muzieknas /mnt/muzieknas cifs auto,rw,uid=mpd,gid=mpd,credentials=/etc/fstab.nas.credentials 0 0
*//MUZIEKNAS.LOCAL is the SMB name that should just work, but might need to use the IP address or IP= option.
**/volume1/muzieknas should be something simple like Music and will match what you can see in windows explorer or the finder.
*'rw' is read write, consider using 'ro' for read-only if you don't need the RW from that machine.
*'uid' is the user id on the mpd server. I actually just use my account here, but it's okay to use 'mpd'
*'gid' is the group id on the mpd server. This will most likely be mpd be default. I actually add the 'audio' group to user accounts and mpd since this resolve other issues
*'credentials' points to a locked down file only readable by root that contains user id, password and domain to the NAS and is in the following format:
username=usernameYou can also secure the file by doing a 'chown root:root <file>' and a 'chmod 600 <file>' if desired.
To confirm that everything worked you can type ls -laF /mnt/ to see the permissions and ownership. Also repeat ls -laF deeper in the directory tree.
You can read the help pages by typing "man fstab" or "man mount" or "man mount.cifs" for more options
Snippet from my fstab file for both an atom and raspberry pi linux mpd servers connecting to my Synology NAS:
# Radio Free Network
//NAS.LOCAL/MUSIC /mnt/nas/music cifs defaults,ro,uid=radio,gid=audio,credentials=/etc/fstab.nas.credentials 0 0
//NAS.LOCAL/HOMES /mnt/nas/homes cifs defaults,uid=radio,gid=users,credentials=/etc/fstab.nas.credentials 0 0
//NAS.LOCAL/BACKUPS /mnt/nas/backups cifs defaults,uid=radio,gid=users,credentials=/etc/fstab.nas.credentials 0 0