Address family not supported by protocol family - SocketException on a specific computer

Question

In an app which I have programmed, I have a java.net.SocketException on a specific computer:

java.net.SocketException: Address family not

Answer 1

1. Open command prompt (windows start button, type cmd in search)
2. Click top left of command prompt, click properties, enable quick edit mode

3. Copy: setx _JAVA_OPTIONS -Djava.net.preferIPv4Stack=true

4. Right click on command prompt, should paste

5. Hit enter. That easy!