if you connect to two networks at the same time (lan and wireless) osx does not know which one is the one that has internet.
so you need to go to preferences (einstellungen) -> network (netzwerk) -> set service order -> drag and drop wlan to the top…
apply… thank you steve jobs… osx is a fine piece of software. sad that you could not enjoy your billions and millions.
you should have given them away… unconditionally.