If a client on the same PC can communicate through the port sharing service, but clients on different PC’s can’t communicate, the Windows Firewall may be blocking external communication.
For Windows 7 or Server 2008 Firewall steps, see http://support.streamsidesolutions.com/entries/22998797-Configuring-firewall-rules-for-NetX-Port-Sharing-Service
Windows XP Firewall Steps:
Here’s the steps to add the NetX Port Sharing service (NetX_Service.exe) to the Windows Firewall exceptions list:
1. Go to control panel and select Windows Firewall.
2. Select the Exceptions tab. Check the list to see if NetX_Service.exe is in the list. If not, click “Add Program” and browse to the application folder and select NetX_Service.exe.
3. After the program is added, select it in the list and click “Change Scope”.
4. Verify the scope of the exception.
5. Retry communication from the remote client.