There are a few possible reasons for this, and it can be worth triple-checking all of them.
First, of course, make sure you're forwarding all of the ports your server needs, and that you're forwarding the right ones. Like a comment suggested, go over the documentation to make sure of things.
Next is to make sure the Windows firewall isn't blocking the relevant ports locally at your computer, although you've said you have that disabled.
At this point it can be worth putting your computer on the router's DMZ as a quick test, just to see if your server is visible at all. If it works this way, something is wrong with your port forwarding setup or the server configuration.
If it still fails, your ISP might have their own firewall or NAT in the way. Does the IP address reported by whatsmyip.org match what the router shows as your WAN IP? If not, try logging into your ISP account to see if there are any firewall or routing settings you can adjust there. Many fiber setups or large building-wide internet hookups will be like this.
If it STILL fails, it might be worth testing with a different server application. Remote Desktop, VNC, any HTTP server can all be good for quickly checking port status.