invalid response to pasv command

I’ve got the ftp working on the drop and on the local network without issue. I can leave the location where the drobo is located and I get the below error when I try to ftp into my drobo after putting in the username/password.

500: The server returned and invalid response to PASV command

I am assuming it is a port issue with pasv, but I do not know where or how to find the default range the ftp software is using for the pasv port range.

Has anyone run across this issue or has any suggestions. Maybe there’s a port range for the passive ftp connection that I can open up on my end…

Also, I found this link for pureftp’d just now. I may try to look into that when I get back to the office.