o² has created with the "More Network" app a possibility to inform the network operator about problems in his network. Now I wanted to use it last weekend, but unfortunately you can't send a message if you don't have a network at all. The reports can't be saved either, so that the messages o² gets can only be delayed - which is certainly not in the sense of network improvement.
From that: if you are a sponsor at a major event, the focus should be on ensuring that the service advertised (in this case mobile phone reception) works without restrictions (i.e. with Internet). There was mobile phone reception, but with internet it looked meagre over the whole weekend. I can't say what the other network operators did at Rock im Park, but at o² there was no internet at all, although EDGE or 3G was displayed in the meantime. Maybe this would have been the time to tell my Fyve self-test to continue.