Go to your router's page, Toolbox tab on side, Game and Application Sharing, click
create a new game or application put what you want into the name thing, put dot at
Manual Entry of Port Maps, click next, make your thing look like

click Add, click Apply, click
Assign a game or application to a local network device at the bottom of page, go to the Device box and choose what you named the port for Blockland and your computer, click Add.