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://tplinkmifi.net.
You may get the wrong DNS Server. You can use the MiFi’s IP address http://192.168.0.1 to login instead of tplinkmifi.net.