Your FritZ!Box may have the ability to generate package traces of your network traffic. If you own a Fritz, click either of the two links below and authenticate yourself on the Fritz.
Select the interface you want to trace by clicking on the corresponding start button. Doing so starts a streaming download in your browser. DO NOT stop this. If you want to stop the trace select the corresponding stop button. After that select the option in your download window to save the trace. Then you can open it to analyze with WireShark (http://www.wireshark.org/).