Can't connect FTP with Ubuntu 16.04

I've installed a new server with Ubuntu 16.04 and the last version of EHCP you suggest.
While I can connect via SFTP to root and navigate on directories, I can't with any FTP userid of domains. Same with net2ftp. Via Filezilla I received this error message: "ECONNREFUSED - Connection refused by server".
Any suggestion?

Resolved. I restarted by consolle ./ftp_server.py and now it's working