Open the web browser and type 192.168.0.1 into the address bar and then Press Enter
Type the username and password in the login page, the default username and password both are admin.
Make sure you are in Advanced section.
Click NAT Fowarding -> Virtual Servers, and then click the Add button
Type 6667 in External and Internal Port; Select Protocol to TCP;
How about Internal IP? Click Status -> Wired/Wireless Clients, and then find your device's IP address.
Type your Internal IP and Press OK.
Click NAT Fowarding -> Port Triggering, and then press the Add button.
Type 6667 in Triggering and External Port; Set Triggering and External Protocol to TCP. Press OK when finished.
Click NAT Fowarding -> DMZ, and then tick the Enable DMZ box; Type your Internal IP; Press Save.
Reboot your router.