Since you're getting a timeout I would assume that your request isn't correct or the URL/path isn't.
If all you're trying to do is learn how to do a Rest integration I suggest dropping the wikipedia example and checking the Rest service path in the Mendix academy - If I remember correctly it does come with an example and more guidance.
Hope this helps.
problem was the proxy settings ...
My browser use an automatic proxy configuration, that was the reason for working in browser. After I put for proxy host+port to the rest service works also in mendix application.