The Windows 2000 system (PC) has Comodo Firewall installed.
I had been able to access this system via Filezilla Client FTP until the update to Filezilla 220.127.116.11 without any problems.
Nothing changed on the Windows 2000 system in any manner; nothing changed with the Comodo firewall.
Just once I updated to Filezilla Client 18.104.22.168, the ability to connect with this PC stopped.
Any ideas or suggestions?