You port forwarding is working perfectly fine.
This problem arises due to the server firewall issue.
Solution
1. Type Firewall.cpl in Run dialog box and hit Enter to open the Windows Firewall.
2. Click on Allow an app or feature through Windows Firewall.
3. Click Change settings.
4. In Allowed apps and features section, scroll down the list to look for Remote Desktop app and put a check mark against it.
5. Click OK.
6. Type gpedit.msc in Run dialog box and hit Enter to open the Local Group Policy Editor.
7. Navigate to : Computer Configuration -> Administrative Templates -> System -> Credentials Delegation
8. Now in the right pane of this location, look for policy setting Allow delegating saved credentials with NTLM-only server authentication and double click on it. Select Enabled and hit Show
9. Finally, in Show Contents window, put the Value as DOMAIN\Computer Name, where you have to substitute your computer name after DOMAIN\. Click OK; Apply; OK. Close the Group Policy Editor.
Ashish
