Maybe is something wrong with the cable (is broken)?

WAN diode is shining after connected?

Please do power reset (reboot) your modem after connected TP-link. You can see that WAN addresses are empty.

I wanted screen from Status TP-link connected to modem. Do you understand?

Are you using IP address or domain address? This is bug in firmware.

You can use MAC Clone function on TP-link and enter 94:de:80:78:54:21 after that please reboot TP-link router. Then you have to connect modem and TP-link by WAN port (blue). Then give me screen from...