I've got a bit of a strange issue in one of our client networks. We recently set up a brand new network for them using a new ASA 5515-X as the main firewall. Things work great (these new devices are very powerful!) but despite my best efforts client computers are unable to access FTP servers outside of our network.
One additional complication is that we have an FTP server inside our network that is externally accessible, so port 21 is NAT'd for that system. However I disabled that rule as a test and nothing changed.
Attached is a sanitized config for our firewall