ProFTPd config via SFTP and FTP
Correct. The solution to have your FTP Daemon works on both FTP/21 and SFTP/2222 is to have <VirtualHost 0.0.0.0> section inside of <IfModule mod_sftp.c>.
I'm sharing this part of my configuration file in /etc/proftpd/proftpd.conf which works fine.
<VirtualHost 0.0.0.0>
SFTPEngine on
Port 2222
SFTPAuthMethods password
RequireValidShell off
SFTPLog /var/log/proftpd/sftp.log
Include /etc/proftpd/sql.conf
SFTPHostKey /etc/ssh/ssh_host_rsa_key
SFTPHostKey /etc/ssh/ssh_host_dsa_key
SFTPCompression delayed
DefaultRoot
</VirtualHost>