Find and Fix FTP issue in code

I have had a software developed that is now causing problems when transferring files from server to server. Current developer says - "this issue is due to the firewall on receiving end" - My server support says "[login to view URL]…ame-was-not-found-in-dns-cache This is the exact same error ANd it was an issue with their Curl syntax The thing is when I try to validate the domain it gives the error almost instantly LIke its not even trying to look up the domain through DNS it seems there is some code that is using curl to verify the information for the domain, and that curl syntax seems to be the issue but I am not sure, just based on the error messages that is what I am seeing" I need someone to get inside my code and find out what is messed up with the ftp connect or curl or whatever the problem is, and fix it so that it works. Files are transferring from my server to other servers. More details upon signing NDA