Asus RT-N12E
The cable from wall socket to the WAN port (number 4)
Router guide
User Manual (there are diffent sub-versions, so…)
https://www.asus.com/Networking-IoT-Servers/WiFi-Routers/ASUS-WiFi-Routers/RTN12E/HelpDesk_Manual/
The manual pages mentioned here are referring to the English version of the manual.
The cable from the wall socket should be connected to the WAN port of the router.
Please log in to the router configuration pages (see the User Manual).
Manual page 22: please select ”Automatic IP” and ”IP Sharing mode”.
Your router should be set to ”Wireless router” mode (see the manual page 53).
Try to find the WAN information: MAC address and IP address.