How should the internal and external ports in the port map correspond to the target ports of the server ports in the server?
Usually, the mapping is from the port of the server to the external port of the gateway device, and the internal or external port is indicated by the IP address. For example, the internal server is192.168.10 port 3389, and the external port mapped to the Internet is your public network address 3389. The internal and external ports can be the same or different.