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.
I tried all the other answers listed here, and they were inefective at preventing requests via IP.
Instead, I opted to deny everything by default (Require all denied and nothing else as your default security model) and white-listing domains explicitly
At some point on my side, I made a backup of "default" NGINX configuration file. This was the cause of the problem since the backup file was also treated as a configuration file, making it a duplicate. Removing this backed-up file fixed the issue.