If this issue still exists, try these following solutions:
Some Web browsers may have cached this page by accident, you can clear the cache and history of your browser and try again.
Besides, you can also try a different browser to access http://tplinkwifi.net.
It is recommended to connect your device directly to TP-Link router with the wired Ethernet cable.
For more solutions, please visit why fail to access tplinkwifi.net.