Hi Zsolt,
I have not tried to run these examples on a Cloud Provider, just on local physical machines. So hopefully we can debug this issue together. We are actively working on our WebRTC examples, so there may be some bumps in the road.
Have you tried setting up the basic WebRTC example through the one packaged with your Engine install? This allows you to run a script and might be a little easier for us to debug with you. Once we know the basic WebRTC example is working, we can move on knowing your WebRTC application is configured correctly.
Are you running the examples from the examples directory? Try placing the example repo code in the top level htdocs. (htdocs > webrtc > example-code-dirs)
Let me know if that helps.
Amara