Please follow the steps below for troubleshooting port forwarding failures on a TP-Link router.
Step 1: Make sure the server is accessible from the internal network
You will want to double-check the IP address and the port number of the server. Check if you can access that server in the local network. If you are unable to access the server in your local network, please check the settings of your server.
Step 2: Check the port forwarding settings in the router.
For DSL Modem Router:
https://www.tp-link.com/en/support/faq/1216/
For Wireless Router:
https://www.tp-link.com/en/support/faq/2799/
For 4G LTE Router:
https://www.tp-link.com/en/support/faq/1685/
For Deco:
https://www.tp-link.com/en/support/faq/1797/
Step 3: Pay attention to the WAN IP address in the status page
If there are still problems, please check the WAN IP of the router. Verify the router is getting a public IP address. If it is a private IP address, which means it's not enough to only open port on the TP-Link, you have to do the same setting on the modem router as well.