If you use an IP restricted FTP server, you will need to whitelist a range of IP addresses currently being used by all the various Cloud Commerce Pro services.
Below is a list of the IP's you need to whitelist:
34.245.142.178
34.245.144.227
63.33.54.83
54.246.236.63
62.128.206.116
212.84.183.157
212.84.183.158
