Step of setting isolation zone
1. Connect your device to the router's network-network cable connection or wifi connection.
2. Manually enter the initial IP address of the wireless router in the web browser:, and then enter the previously set password to log in to the user interface.
I suggest:
You can also delete the set DMZ by removing the DMZ. [How to remove DMZ from ASUS RT-AC86U router]
[How to set a port trigger for ASUS RT-AC86U router]
[How to set up automatic connection to DNS server for ASUS RT-AC86U router]