When your site goes through CloudFlare cache servers, it will not work to have your own domain as the host on ftp (it would try to connect the cache server of CloudFlare as that's where the domain points).
Try using the server url for host in FTP. Optionally create a subdomain ftp.domainname.com which is set to bypass cloudflare (was a while since I tested cloudflare, but there should be an option for setting certain domains to not be cached).
The same problem would apply to using mail.domainname.com for accessing email in your mail client without having that set to bypass, your mail client will try to login on the CloudFlare server. In this case using the server url would also work as an option though.
It was the small details as above that steered me from using CloudFlare.
That would be such a waste of subdomains on a free plan thought. Yes, CF does have a Cache Avoidance feature; I could try that. That idea you mentioned is actually pretty brilliant though.
I posted this on the Discord Request for Support:
“Can an admin help me solve an SSL/TLS/FTP issue? I have a Custom Hostname in my SSL/TLS and it’s setup under my DirectAdmin so is my CA- but when I go to login over FTP it says login failed error “530” and still tries to issue the x14 server cert. This issue lays inside my SMTP issue too; my SMTP only works if I use it with no SSL or TLS but when me and my server send emails they’re encrypted by the SSL/TLS.
Any idea what’s going on? I can’t figure it out. I have DirectAdmin and Cloudflare in “conjunction” with everything. Doesn’t make sense.”
^Thats what my current issue is now.
I’m trying to polish off a authentic end-to-end communications so I know my data can be secured for my users; that way when I let them use Cloud Services, Websites, Emails, etc. they can go through my domain and not an IP Address or a Sub-Domain from a 3rd Party.
Thanks in advance!