When a PC is set as a DMZ (Demilitarized Zone) host on the local network, it is fully exposed to the Internet, enabling unlimited two-way communication between internal and external hosts. The DMZ host becomes a virtual server with all ports open. You can set the PC as a DMZ host when you are not clear which ports to open in special applications, such as webcams and database software.

Note: The DMZ is more suitable for situations where the user does not know which ports to open. After this function is enabled, hosts in the DMZ are completely exposed to the Internet, which may cause security risks. If you do not use DMZ, disable it in time.

Practical example: I want my computer to be able to play online games without any port restrictions. For example, when playing an online game, you can log in normally but cannot team up with other players due to some port restrictions. To resolve this issue, set your PC as a DMZ host and open all ports.

Here take WAVLINK WL-WN531AX2 router as a demonstration to configure DMZ,
Steps:
Set your PC to a static IP address to be in the same sub-net of the router (default IP address is 192.168.10.0), for example 192.168.10.100 .

Please log in to the web-based setup page of the WAVLINK router to configure Guest Wi-Fi
2.1 Connect WAVLINK router via its Wi-Fi SSID or an Ethernet cable.
2.2 Launch web browser and type URL http://192.168.10.1 or http://wavlogin.link in the address bar,  the login screen will appear.

2.3 Enter the Password, If it has not been changed, the default is "admin".

3. After logging in, you will see the Home web page of the WAVLINK router, click "Advanced" and choose “DMZ Management”

Select Enable and enter the IP address 192.168.0.100 in the DMZ Host IP Address filed

Click “Save"
Then you’ve set your PC to DMZ host and now you can make a team to game with other players.