What does the Port Forwarding option do on MyCloud (gen 2)?

[Bennor]

Edit just realized Pokeefe started the other two threads I linked to and were still having the same problem with Acronis.

https://community.wd.com/t/fail-to-connect-between-acronis-ti-2016-and-mycloud-gen2/176633

https://community.wd.com/t/mycloud-ftp-server-gives-550-error-to-mlst-command/175979