Once again running the preview I saw this message.
Who that can tell how to solve this problem?
Develop games in your browser. Powerful, performant & highly capable.
Did you follow this tutorial?
scirra.com/tutorials/247/how-to-preview-on-a-local-network
Now I get a new error code (5).
Oh, I was able to solve the problem.
This is a problem with a busy port.
I use Insiders build WIn 10, and apparently they added something to the system that took port 50000.
I set the port 55000 and it worked.