I was able to access the ftp server fine, until I added ssl_enable=YES.
Did you also create a certificate? You might want to have a read through this howto
(it is a touch dated, but I think it is still largely accurate) for some tips on what you need to do to enable SSL for vsftpd.
If you did create a cert, have a look in the log files and see if vsftpd is having trouble using it. Also be sure that your FTP client can support SSL, not all of them can.