if in same lan ,it’s OK .

I think because of no DDNS , so ..

1. Install webmin for config DDNS here

mkdir webmin
cd webmin
wget http://prdownloads.sourceforge.net/webadmin/webmin-1.580.tar.gz
gunzip webmin-1.580.tar.gz
tar xf webmin-1.580.tar
cd webmin-1.580
sudo ./setup.sh /usr/local/webmin

2.Upgrade webmin

3.not seen ddns on webmin , where?

4.do it as this link   and update rc.local this link

5. Further more than 9091 port forward, there is one port that need to config for open to torrent out 15413 (look at transmission option).