Dlink Extender is not working

Ensure that you are using the correct IP address for the router, as well as the correct port (some use 8080 instead of the standard port 80).
The wireless settings may not be configured properly and wireless access to the admin interface might be disabled.

Enter the right Ip address and Check your wireless connection first and try to login and set up the D-link router. The correct IP and stable internet connection also helps you to login to the D-Link router.
https://dlinkapnet.net/dlink-extender-is-not-working/