Definitely recommend hotel Noris in the centre of the Lindau island 3-4 minutes walking distance away from the train station.
It is very central, clean and our host Marketa was very friendly. She even prepared the breakfast earlier at 06:30 (than the normal starting time of 07:00) for us to catch up with our schedule in the conference. I really appreciated that.
The internet connection was good, compared to my colleagues' hotel internet connections around the rest of the hotels in the island.