I would first try to use the DMZ option instead of port forwarding. Port forwarding rules on some routers can be confusing but the DMZ all you need to get correct it the IP of the machine on your network running the service.
Two other things to check.
The most common cause we see when people have spent some time troubleshooting this is they do not actually have a public IP and will never be able to get port forwarding to work. Check the IP in your router that is assigned to the wan port, the exact menu varies a lot between routers. If this IP does not match a site like whatsmyip you have a private IP and can not use port forwarding.
The second one is be sure you can access the server function from another machine on your lan using the local IP. If you are running port scanners from the internet there must be a program actually active on the port that will respond.