Windows – Why do some FTP Clients not connect to a IIS7 FTP Server

I have a Windows 2008 R2 Server with II7. I have installed the FTP server. I can connect to it fine with Dreamweaver CS5 on my Mac. I can connect to it fine with Cute FTP 7 Professional on a PC. I cannot connect to it with Filezilla on the Mac. With Filezilla the operation times out after a while. Some of my clients cannot connect to it no matter what FTP client they try. We've been over the connection credentials (host, username & password) and are pretty certain they are all correct.

Can anyone shed some light on this situation. I do note that the programs that I can connect with are older. Perhaps there are some advanced security settings on newer clients? The settings I use are connecting via FTP, port 21, basic authentication … a bunch of other setting that I do not understand.

Filezilla Logs (which doesn't connect):

Status: Resolving address of ftp.steadyserve.net
Status: Connecting to xx.xx.xxx.xxx:21...
Status: Connection established, waiting for welcome message...
Response:   220 Microsoft FTP Service
Command:    USER xxxxxx
Response:   331 Password required for pedroo.
Command:    PASS *******
Response:   230 User logged in.
Command:    SYST
Response:   215 Windows_NT
Command:    FEAT
Response:   211-Extended features supported:
Response:    LANG EN*
Response:    UTF8
Response:    AUTH TLS;TLS-C;SSL;TLS-P;
Response:    PBSZ
Response:    PROT C;P;
Response:    CCC
Response:    HOST
Response:    SIZE
Response:    MDTM
Response:    REST STREAM
Response:   211 END
Command:    OPTS UTF8 ON
Response:   200 OPTS UTF8 command successful - UTF8 encoding now ON.
Status: Connected
Status: Retrieving directory listing...
Command:    PWD
Response:   257 "/pedroo" is current directory.
Command:    TYPE I
Response:   200 Type set to I.
Command:    PASV
Response:   425 Cannot open data connection.
Command:    PORT 10,0,0,8,210,49
Response:   200 PORT command successful.
Command:    LIST
Response:   150 Opening BINARY mode data connection.
Error:  Connection timed out
Error:  Failed to retrieve directory listing

Dreamweaver logs (which does connect):

< 220 Microsoft FTP Service
 > USER pedroo
 < 331 Password required for pedroo.
 > PASS
 < 230 User logged in.
 > PWD
 < 257 "/pedroo" is current directory.
 > PWD
 < 257 "/pedroo" is current directory.
 > CWD /pedroo
 < 250 CWD command successful.
 > PWD
 < 257 "/pedroo" is current directory.
 > CWD /pedroo
 < 250 CWD command successful.
 > PORT 10,0,0,8,211,100
 < 200 PORT command successful.
 > TYPE A
 < 200 Type set to A.

I've tried changing the mode form passive to active. I get the same error.

TIA,

Jay