We do enable firewall rule for one side on FTPs, from source IP/FTP client to destination IP/FTP server with destination port/TCP/21, but looks like Windows default FTP connection works like the FTP server establishes the data connection by TCP/20 to the Client FTP, and it worked without enabling the reverse side rule by TCP/20, suddenly it blocked recently, and TAC this supposed to be open from the first, anyone experienced same thing?
