First, you need a primary connection of the mobile phone or the computer with the extender network in order to log into the Wavlink AC1200 Setup account. To use the extender, you need to plug the extender into the power supply and turn it on. But, if you face any error like this, then use these points. 

Your appliance is not WiFi enabled for sure & the network setup is still left open. Following these check, if the SSID credentials of the extender are correct. After that, you have to use the default SSID Wavlink_EXT, If you are up to connecting your device to the extender networks. Now to redirect the login window you have to type, wifi.wavlink.com to log in to the web interface of the wizard in order to log in. Now, just Sign In to the range extender login page. Although you can also configure it with the 192.168.10.1. The IP address of the login wizard. This is the shortcut to logging in to the portal of Wavlink. Now, type your administrative password and Username in the Login Window of the extender. Finally, by clicking the button you can log in to the account of Wavlink.