

Have you tried copying configuration files between the problematic systems and yours? Have you tried bringing one of the problem machines and plug it in where your workstation is, or take your workstation and plug it in where the a problematic computer is located? Have you done simple networking tests to verify it isn't something simple like DNS issues or how the FTP server address is being entered? Is your machine on a special VLAN, connected to a different switch, bypassing any hardware the other computers are connected to, or does your computer/profile have special permissions on the firewall/proxy/etc.? What type of connection are you using? Standard FTP, plain insecure connection? FTPS Implicit or Explicit, secure connection? SFTP SSH? If using a secure connection, what type of Certificate are you using? Generated by the FTP Server, self-signed, 3rd party? In that case, what is the FTP Server that you are trying to connect to, and what software is it running? Since you are mentioning multiple computers, I can only assume that you are referring to FileZilla Client. FileZilla has both a Client and a Server component.
