I analyzed the messages exchanged between the browser and the server and thought the server might be confused by the User Agent setting. Especially because everything worked perfectly fine in Firefox on the same machine. And I could open maps on the Android smartphone being used to relay the connection.
So, Open Source devs to the rescue. There is a command-line option to set the User Agent when starting Chromium-based browsers. It is as simple as running
or whatever else you want. More appropriate would, probably, be to use "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.6 (KHTML, like Gecko) Chrome/20.0.1092.0 Safari/536.6" as that is the user agent string for one of the later Chrome browsers on Windows.