Full FTP instructions are here: https://galaxyproject.org/ftp-upload/
I just now tested the Public Galaxy Main server https://usegalaxy.org and it is accepting connections. I used Filezilla with all default settings. Entered the server name (as usegalaxy.org), email address (case sensitive), password, clicked to quick connect, accepted the security cert pop-up, and proceeded with a successful data transfer.
Double check your settings and try again. If problems continue, there may be a firewall, and contacting a local admin/ISP provider could help to clarify if a firewall is a factor and how to get around it.
Each Galaxy server is independently administered, so if working at a different site (check the URL), contacting the owners of that server might also help.
Thanks! Jen, Galaxy team