Lacie Ethernet Disk Mini uses XFS as its file system. Attaching a USB flash disk whose default FS is FAT would be fine, but attaching a Freecom 1.5TB is no good. Reformatting the latter to EXT4, NTFS or XFS doesn’t cut it either. And never mind if you’re confused with the interface difference between Ethernet and USB network.
To those who gets dizzy with the pros and cons of XFS, ZFS and EXT4, here’s some links. Oh and not mention BtrFS which is the future of EXT4.