Logging into your router's interface is necessary to configure the TP-Link router settings. Tplinkwifi.net, the default gateway for your router, is what you use to access the login page for the TP-Link router. You can access the advanced wireless security settings by entering this gateway into the address field of your browser.

https://www.router-solutions.com/configure-tp-link-router-as-a-wireless-access-point-secure-network-by-changing-ip-address/