Can connect RDP from windows to ubuntu in local but not from the internet

I'm facing a lil problem here.

• I've installed xrdp on my ubuntu 21.04 and enabled it
• I've open 3389 port tcp on my router for my ubuntu pc
• I've disabled firewall both on WIN10 and ubuntu

I can connect local to ubuntu, no problem, but when I try from the internet "Can't connect" error message...

Got public IP from whatmyip , tryied with IP:PORT and just IP but nothing works

What did I miss ?

Thanks you for anyhelp

There may a network firewall issue, you could try following command to check does you external ip could be access from outside of the world.

nmap -p 3389 your_public_ip 
# make sure the test client is not inside of your home network (internal network)

Or there is another options is use online port scan tools such as

https://www.whatismyip.com/port-scanner/