FAT32 drives are not writeable as a share, but the device can back up to a FAT32 volume.
The filesystem of the internal drive does not affect Mac compatibility, since any computer will not have to access the filesystem on the device directly. Computers use the SMB protocol to access files on the device.
Okay so what your saying is that by using the backup option (not the drive share) technically the USB extension drive does write the files to a Fat32 file system!
So can you then take the backup drive and mount directly on a MacOSX machine and access the files directly?
Or is it in some Buffalo backup file system?