Here's my problem in a nutshell:
1) My ISP blocks FTP ports on their side (not on the router, so I can't control that)
2) My Buffalo NAS won't let me change the default FTP ports
3) My ISP's modem/router won't let me set the outside and inside ports separately for port forwarding. ex., I can forward port 666 to an internal IP address only on port 666...not port 666 (WAN) to port 20 (LAN)
This basically means that both the ISP and the Buffalo NAS make it so I can't use FTP. I've thought about perhaps mapping the NAS's shares to network drives on one computer and having THAT computer run an FTP server. I've heard there are network issues with doing it that way though.