I am very happy with my TS-112P, but i'm...

I am very happy with my TS-112P, but i'm trying to map the ftp as a local drive. Novel Netdrive seemed to do the trick but when i'm out of the LAN i often get an empty folder. FTP clients like filezilla works fine, so it's not a matter of opening port on the router. Any ideas or altrenatives to netdrive to be able to treat the remote FTP as local or network drive? Thanks in advance!!!