Passive Mode

To enable FTP Passive Mode on Plesk systems, you will need to first edit the proftpd.conf file in /etc/

nano /etc/proftpd.conf

Then find the following lines

# delay on login off (are included on newest Plesk) 
IdentLookups off
UseReverseDNS off

Under the lines above, add the following and save the file.

# Custom directives
PassivePorts 60000 65000

Now restart xinetd

service xinetd restart

Once xinetd is restarted, you need to add the port range to the Plesk Firewall. Modules > Firewall > Edit Firewall Configuration > Add Custom Rule
Select Incoming, Allow, then add the port range 60000-65000, TCP and OK.

WHM/ cPanel

nano /etc/pure-ftp.conf

PassivePortRange 60000 65000

service pure-ftp restart

Now, log into WHM and edit the firewall:

ConfigServer Security & Firewall > Firewall Configuration. Add port range 60000:65000 to the TCP_IN rules and save!

Update: Configuring the Passive FTP Mode on a Microsoft Azure Instance
See this article: https://docs.plesk.com/en-US/onyx/deployment-guide/plesk-installation-and-upgrade-on-public-cloud-services/installing-plesk-on-microsoft-azure/configuring-the-passive-ftp-mode-on-a-microsoft-azure-instance.79079/