Success! Finally ;)
It turned out to be a case of too many rules in one sense, and not enough in another. The tutorial you referenced was the one I followed, but what had screwed me up was the last two rules shown at the end of the tutorial. I didn't realize that it was referring to the collection in Firewall->Rules->WAN, so I hadn't properly defined the rules. Once I cleaned things up, and seeing your comments about not needing more than than one PF rule, I got it working by simplifying the rules.
Interestingly enough, it works perfectly with FileZilla as the FTP client, but not using the Windows command-line FTP client. And I am using a remote system as the client source. I have a rented server in a facility about 1,000 km away. I connect to it using RDP and then come back to my network using various protocols. In this case I needed FTP as the protocol, and that now works perfectly.
Now to set up another FTP server using the same approach.
Thanks again for the assist.
It turned out to be a case of too many rules in one sense, and not enough in another. The tutorial you referenced was the one I followed, but what had screwed me up was the last two rules shown at the end of the tutorial. I didn't realize that it was referring to the collection in Firewall->Rules->WAN, so I hadn't properly defined the rules. Once I cleaned things up, and seeing your comments about not needing more than than one PF rule, I got it working by simplifying the rules.
Interestingly enough, it works perfectly with FileZilla as the FTP client, but not using the Windows command-line FTP client. And I am using a remote system as the client source. I have a rented server in a facility about 1,000 km away. I connect to it using RDP and then come back to my network using various protocols. In this case I needed FTP as the protocol, and that now works perfectly.
Now to set up another FTP server using the same approach.
Thanks again for the assist.