To connect over the internet, you will require alternate IP addresses for your MetaFrame servers.
External clients need to resolve the internal (LAN) name and IP of your MetaFrame server, which, presumably, is not advertised on the internet! I'd assume you have a modem or router for connection to your ISP, which will hopefully perform NAT.
Try using the altaddr command on your MetaFrame server(s), and setting your remote clients to connect to use the alternate address. There are some docs on Citrix's site on how to do this.
Hope this helps CitrixEngineer@yahoo.co.uk