Why port forwarding feature is not working on TP-Link ISP-Customized Router?

Introduction

This article provides some suggestions for troubleshooting potential causes of failed port forwarding.

Troubleshooting

Tip 1. The port forwarding settings are correct

• If you want to use a special WAN, you need to choose it as the interface. Ensure that the correct WAN is chosen.

• Ensure that the internal IP address is the actual IP of the target device. It is recommended to use a static IP.

Tip 2. The target device is online in the local network

You may use the ping command to confirm whether the device is reachable. Example: ping 192.168.1.100. The corresponding service (e.g., Web service, FTP, remote desktop) should be enabled on the device.

Tip 3. WAN interface has the WAN IP

Ensure that you can get a reply from the WAN IP via the ping command.

Tip 4. No dual routing problem

To avoid the dual routing problem, it's suggested to use a single router instead of an optical network terminal and a router. It is recommended to set up a bridge mode or configure port forwarding on the upper-level device as well.

Tip 5. No firewall issue

To determine whether the Windows firewall or third-party security software is blocking port access, temporarily disable the firewall for testing to confirm whether it is a firewall issue.

Tip 6. The port is not occupied by the other services

To determine whether other services occupy the port, you may follow the instructions below to test:

Step 1. Open the command line interface.

Step 2. Use the command below to check if this port is occupied in the server.

netstat -ano | findstr :xx (for windows) ,sudo lsof -i :xx(linux&mac)

• Example for Windows

netstat -ano | findstr :80

• Example for Linux & Mac

sudo lsof -i :80

Step 3. If there is a process ID listed in result of step 2’s command, use the below command to end the process, then check whether the port forwarding works.

taskkill /PID xxxx /F

Note: xxxx is the ID of the process.

Here is an example for windows:

Step 1. Open the command line interface by searching CMD.

Step 2. Input command

netstat -ano | findstr :8080

Step 3. Input command

taskkill /PID 36316 /f

Note: (PID 36316 is the process ID on the right).