Winscp not connecting with public ip but working with Internal ip

Hi when trying to connect winscp from windows server 2012 to linux. We can able to connect with the private ip of target machine. But when i try to connect with the public ip of the server it is not working. I checked with Network team tbey are saying there is nothing wrong in their configurations. Pls help

This does not look like WinSCP issue. Unless you can connect with any other client using the same protocol.