Failed to start service :
- Starting ftp server proftpd
- IPv4 getaddrinfo ‘server’ error: Name or service not known
- warning: unable to determine IP address of ‘server’
- error: no valid servers configured
- Fatal: error processing configuration file ‘/etc/proftpd/proftpd.conf’
Your system does not have a fully qualified domain name. You MUST have a fully qualified domain name to run almost all of the services on a hosting system–not just ProFTPd. Postfix will also fail in numerous ways without it.
Browse to Webmin:Networking:Network Configuration:Hostname and DNS Client and set the hostname to a fully qualified domain name (like ns1.example.com or primary.example.com or host1.example.com etc.). You’ll also need to make sure this name is added to the Host Addresses list with the public primary IP address of your system.