In this case you can use the server's IP address for FTP server name when configuring your FTP connection.

You can find the server's IP address by logging in your Customer's area and going to My Account -> Manage (next to your account).

You can also use the server name of the server hosting your account. For example, if you are a SiteGround customer and you are hosted on siteground200.com, you can use siteground200.com for FTP host.