2BrightSparks
I don't know Indy 10 but from what information you posted the PortIP propery in the SmartFTP FTP Library seems to be the same as the ExternalIP property in Indy 10. You need to set the PortMode property to PortModeManual before the IP in the PortIP property is used.
To limit the ports used for a PORT/EPRT command please see the IFTPPortPool Interface. You can set the range with the SetPortRange method.
Regards,
-Mat