1. Set up the primary router (wired) using any IP address (usually 192.168.0.1) and turn on the DHCP function (Dynamic Host Configuration Protocol).
2. Set up the wireless router and plug it with the cable from the primary router. Notice that the cable should be plugged in a LAN port (not the WAN port which usually located separately next to the LAN ports).
3. Set the IP address of the wireless router differently from the wired router to avoid IP conflict. In this case, the IP address for the wireless router must differ from 192.168.0.X (I set it as 192.168.1.1 for for convenience).
4. Turn off DHCP function of the wireless router in order to avoid duplicated IP assignment.
The preceding procedures turn off the routing function of the wireless router but only use it as a wireless transmitter. In this way, IP assignment conflict can be avoided while connecting both wired and wireless devices to the Internet.