Max!Cube can't establish connection

Hi guys,
I bought a set of 5 thermostats and the maxcube. It all works, but I can’t get Hass to find it. I configured everything like on the components page and took the IP right from my router page. Hass is telling me, that it couldn’t establish a connection. Did they change the ports or something like that?

Keep in mind that the Cube only can handle one connection at a time. When you are logged in via the (Windows) app, HASS cannot connect.