- Check if connection between device and extender is intact, any limitation in connection may create problem in opening the setup website.
- Clear cookies and cache of your browser and also try to change the browser.
- Try changing the browser. Use edge, chrome or firefox for seamless configuration.
Not every device supports the WPS, it may be that your router doesn’t support WPS. In such case try alternate way to setup the extender.
Login into your router page and look for WPS setting, enable the WPS from the router page and try again.