When using a D-Link Router simply browse to the Adminstrator-Interface, which is normally at http://192.168.0.1/

Go to to Advanced -> Virtual Server ..

• Select "Enabled".
• Enter a Name, e.g. "visiongs".
• Select Protocol Type "TCP".
• When using the implemented Http Server, enter the Port where the Http Server is running on as Public and Private Port. When using the implemented Streaming Server enter the Port where the Streaming Server is running on as Public and Private Port.
• Select Schedule "Always".
• Press "Apply".

Thats it :-)