The above issue is occuring because of Cloudflare proxying being enabled on your domain.
Since Cloudflare is being used on your domain, therefore the DNS record of mail would be pointing to Cloudflare's ip addresses/servers, instead of directly pointing to SiteCountry's servers.
In this case, I can recommend you two solutions to the problem.Use your Control Panel Login URL's Hostname as the Host in FTP Client.
Go to your Cloudflare Account, add a DNS record of type : CNAME, Name = ftpx, Value = Control Panel hostname ( for example : ruby.scnservers.net)
Once done, wait for 2-3 mins and retry connecting to FTP client with host as ftpx.example.com
We hope this solves the issue. Do not hesitate to let us know if the issue is still unresolved.