The following error is shown during an attempt to establish a connection via Filezilla:
Status: Connecting to example.com:21...
Response: fzSftp started, protocol_version=8
Command: open "firstname.lastname@example.org" 21
Error: Network error: Connection refused
Error: Could not connect to server
Attempting to connect with SFTP protocol instead of FTPS.
Go under FileZilla > File > Site Manager > New Site, choose the appropriate protocol (FTPS), input the credentials and connect again.