Hi, If you have any issues about port forwarding or the opened ports are still closed, the following suggestions will provide you with some guidance.

1. Failed to configure port forwarding.
First, please refer to this link-How to set up Port Forwarding feature on the Deco? for the detailed configuration guide of port forwarding.
Then the following situations are what we have received from the users,

• The device is not on the “Select from Device” list.

Please check whether the server is used a static IP address. If yes, please change it to DHCP

Most of the time, Devices, such as NAS, NVR, Virtual Box, and PI-Hole are usually set up with static IP addresses, instead of DHCP, if you do not use to use DHCP, this link would provide a workaround.

Forward port to missing device

• Some error messages pop out during the configuration.

The troubleshooting depends on the error code and please comment below with a screenshot of your error message.

2. Port forwarding is set up correctly, but ports aren't open.

• First, please check whether you have a public IP address under Deco APP>More>Advanced>IPV4.

If this IP is a private address, you might have a double NAT issue and the port is blocked by the ISP gateway.
The available solutions are:

1. Set up Deco as an access point under Deco APP>More>Advanced>Operation mode;

2. Open the same port for Deco on the ISP gateway.

• Check the firewall settings on the server.

Windows firewall will block the connection from the different subnet, and it will divide the difference according to the network location you have chosen.

Please refer to this link to check whether you have a public IPV4 address and the LAN server is on the Public network profile:

https://www.tp-link.com/en/support/faq/785/

If the IPV4 IP is a public IP address, the configuration has no obvious mistakes, your case needs to be under further analysis, please comment below with the following details:

1.Please make sure UPNP disabled under Deco APP>More>Advanced.

2. Which ports did you wish to open? For which local devices?
3. Are you able to access this server via the same port on a local client?
4. How did you find out the port is still closed?

    ---If you have enabled TP-Link DDNS, except testing via the DDNS, please also test whether the server is accessible remotely via WAN IP address.

We do need more cases to complete the troubleshooting guides and please let me know which one is quite similar to your case, and if any of the suggestions works.
Thank you very much.