If you forward a port, it only applies to the computer you apply it for. And if you wanted to re-apply it for other computers on the network, they would require separate port forwards & using diffrent port numbers.

It is possible for LW to work even if the brick wall icon is there for some people. eg: I have a port forwarded for one computer. If I use it on another computer during the same session, then LW says port unavailable or brick wall.

Who is your ISP?