First, determine till where the FTP client is working; if you are able to login with FTP but do not see the directories or files show up and get a timeout you will need to switch your FTP client to Passive FTP.
If you can not login to your FTP account; check if you have a firewall installed which may block FTP connections; also if you use a firewall on your system you should use Passive FTP. If you can connect and userid-password is asked but you fail to login you probably use the wrong credentials to log in; you should use username+domainname.tld as userid where the @ is replaced by the + sign.
How to set Passive FTP in different FTP programs:
Beyond compare Tools > Options > FTP > Firewall / Proxy and check the Passive Mode box
FileZilla File > SiteManager > Transfer settings and select the Passive Mode radio button.