When connecting to cpanel66's FTP server I run into the following problem if I use AUTH TLS:

227 Entering Passive Mode (67,228,55,48,146,52)
Connecting FTP data socket...
The connection failed due to an error or timeout.
I'm out of ideas on what could be causing this. It authenticates fine, but can't open the data connection. It just sits there and times out.

- Plain FTP to this server works
- SFTP to this server works
- FTP with TLS works on another server (one on my network)
- I've disabled my firewall
- I've played with every relevant setting I can find in the client
- I've tried other FTP clients, identical result

Obviously I can sidestep this issue by using SFTP or active mode, but I'd like to know what the problem is and resolve it if possible. I would appreciate any suggestions.