It sounds like you have taken the necessary steps to enable RDP on your Windows 11 Pro machine and configure port forwarding on your router. However, since you are unable to connect to your machine from outside your network, it is possible that your ISP is blocking incoming traffic on the RDP port.
To confirm this, you can try changing the RDP port to a different port number (e.g. 3389 to 3390) and update the port forwarding rule on your router accordingly. Then, try connecting to your machine using the new port number from outside your network.
If you are still unable to connect, you may need to contact your ISP to see if they are blocking incoming traffic on the RDP port. Alternatively, you can try using a VPN to connect to your network and then access your Windows 11 Pro machine via RDP.
The second option, using VPN is the advisable one, opening RDP on the internet will subject your pc to brute force attacks by botnets & hackers. It might not be long before your setup is breached if you do.