To set up port forwarding:
    1. go to Network > Firewall
    2. make the dropdown be "Forward", and click "Add"
    3. in the dropdown, choose "Destination ports", and click "Add"
    4. enter the incoming port on the top section
    5. in the bottom section, enter the same port, and enter the internal IP address
    6. click Save
    7. click Apply

     
To make sure you always have the same IP address:
    1. go to Status, and copy the MAC address of your computer
    2. go to Network > Hosts
    3. in the "Static IP" section, set up the MAC address to always return the same IP from now on
    4. click Apply