Ok, here's something to try. Go to your ftp server, and where it says something about report ip address in passive mode, put the internal network ip of your ftp server. In my case 192.168.0.5, not your external ip. I think it has something to do with trying to report the address outside the network,...

Having the exact same problem. Can't connect over 3g with my droid x2. I KNOW i used to be able to connect. Tried various settings, the only thing that works is turning on wifi. A fix of limited usefulness.