Hello,
1. Ensure that your device has connected to the router
2. Open a web browser and enter 192.168.0.1 or tplinkwifi.net in the address bar and give it a go.
3. Otherwise, please check the default gateway of your device and use it to access the internet: https://www.tp-link.com/en/faq-838.html
4. Meanwhile, you can use different web browser and devices to access.
5. Besides, you can try to reset the router and login with the default username and password.
Here is an instruction you can refer to: https://www.tp-link.com/en/faq-2236.html
May it help.
Good day.