Ftp works from internet not from internal network.

My network is a little odd. I have a firewall/router combo that goes to my server and also to a second router that runs the internal network. I cannot change this setup because of the phone system we use. I have the firewall setup to forward trafic on port 21 to my server. The ftp I am setting up on the server works from the internet or externally but will not work from the internal network unless we put the computer's internal ip address in. So I want to be able to access it from internally and externally by typing in ftp://publicip that works externally but internally I have to use ftp://priviteip

That is normal behavior for a server with an internal IP address. Routers do not loop connections back inside to a private address.

The only way around it is for you to manually enter the name in your computer's hosts file. Assuming you are running some recent version of Windows, it is at c:\windows\system32\drivers\etc

Simply open up the hosts file in a plain text editor like Notepad and follow the example.