I was just able to get this accomplished with stretch version and NFS to my Synology NAS.
Create the mount point you want: sudo mkdir /mnt/NAS
Mounted it manually first: sudo mount -t nfs 192.168.1.100:/volume1/video /mnt/NAS
Checked to make sure the path worked: cd /mnt/NAS ls -al
All was good, so put it into fstab for mounting at boot. I put this in at the very end of fstab: sudo nano /etc/fstab 192.168.1.100:/volume1/video /mnt/NAS nfs defaults 0 0
I rebooted and verified that it was there.
I hope you had the same success I did!