One of a few locations I’ve found here in Berlin so far with totally open Wi-Fi access. The Einstein Kaffee, located at Kurfürstenstraße 58, provides all the expected coffee drinks and pastries. They have indoor and outdoor seating and a fast internet connection.
Next door is Sopranos, and Italian restaurant serving pizza, pasta and salads. They have their own T-Mobile/T-Com hotspot, but you can easily get on the Einstein Kaffee network, even from inside the restaurant, if you don’t have a T-Mobile subscription.