Dreamweaver 9/CS3 FTP stopped working, cannot connect any more

Dreamweaver 9/CS3 is no longer able to make ftp connections to specific servers.

To be clear: It was working, then stopped working.

I can still connect to the servers with filezilla, so the problem is not on the server end, and not with the credentials.

I can connect to other servers with dreamweaver, so the problem is not with my computer, router, firewall, etc.

I have a couple site definitions which point to the same host but different subdirectories. Both do not work. I created a test to an anonymous ftp site and it worked.

It seems like somehow some dreamweaver file specific to the host in question got corrupted.

I have tried many potential solutions, everything I found online, other than reinstalling DW as this does not seem to fix the problem for anyone else that tried it.

Tried deleting the dreamweaver preferences folder and registry entries.

Tried exporting the site definition, deleting, and importing.

Tried creating new site definition.

Tried deleting the ssh_hosts file.

Tried using the IP address in place of domain name for ftp host.

Tried appending host sftp port number :22 to right side of ftp host name.

Tried unchecking Use FTP performance optimization in Server Compatibility

Upload design notes is turned off.

Am using a wired connection, not wifi.

The site definition > advanced settings > remote info has Use passive FTP checked although it and Use Firewall are greyed out due to Use Secure FTP (SFTP) being checked. It had been working with those settings. I have tried every combination of each of those boxes checked and unchecked. I have also tried modifying the Firewall Settings: FTP time out 10 seconds, 60 seconds, 120 seconds; FTP connection unchecked disconnect after 30 minutes idle.

I get different results with each setting. E.g.:

With Secure FTP (which used to work in dw and still works in filezilla) it fails in about a half second.

It pops up a dialog box that says: "An FTP error occurred - cannot make connection to host. Your login or password is incorrect. Please check your connection information."

(Remember, the credentials are correct and work in filezilla.)

The ftp log shows nothing new but a new blank line.

I noticed that the ssh_hosts file does not get re-created, which seems to indicate its not even getting to that point.

With Use Firewall it delays for several seconds and I click cancel because it would connect much quicker if it was going to. FTP log shows nothing.

With Use passive FTP only it seems to connect. Then gives a dialog box that says: An FTP error occurred - cannot get remote folder information. Dreamweaver encountered a network or file system error. Please try the operation again, and contact the administrator if the error continues to occur.

FTP log shows:
< 220 FTP Server ready.
> USER (username)
< 331 Password required for (username)
> PASS
< 230 User (username) logged in
> PWD
< 257 "/" is the current directory
> PWD
< 257 "/" is the current directory

> CWD /host_directory
< 250 CWD command successful
> PWD
< 257 "/host_directory" is the current directory

However it was working not with passive ftp only but with sftp which shows passive greyed out.

So in summary, filezilla works, so it's not the host, it's not my hardware or firewall, it's not the credentials, it is specific to DW and specific to a certain host. It adds nothing but a blank line to the ftp log. The ssh_hosts file does not get created. It gives the error message: "An FTP error occurred - cannot make connection to host. Your login or password is incorrect. Please check your connection information." (But again it's not the login credentials as they work in filezilla.)

So what could that be? A certain file related to a specific host that got corrupted?