I recommend that you run a trace to figure where the problem is.
If you look only at ftp for example,
run on the server
Code:
sudo tcpdump -vvXns0 port 21
Do the ftp from the remote location and see if any packets are received at your server.
If you dont see them, then either your port mapping is wrong or not working, or your ISP is blocking the port number your using
If you see traffic coming in, see if theres a response.
If there is, you could post the results and I could try and see if there are any clues.
Cheers
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