@MinZhou Because we are testing Internet connectivity, you don’t have to reset the router. Simply change the SSID, or turn off WiFi should work.
But since you’ve reset the router already, you’ll need to go back to the initial setup. You should be able to load the router console with 192.168.10.1.
To keep things simple, disconnect all wires from the pcWRT router. Then connect the power cable only, wait till it’s fully powered up. The SYS and WLAN LEDs should be solid on. Then connect your PC by Ethernet wire to a LAN port on the pcWRT. Load 192.168.10.1 to perform initial setup.
If the above step is successful, connect the pcWRT WAN port to a LAN port on your old router. Again, connect your PC to a LAN port on the pcWRT. Load 192.168.10.1 and look at the Status page. Is Internet up or down?