The most popular consumer hardware router that is used in Germany is without doubt the AVM Fritz!Box. The demand of secure communication is increasing and people are thinking more about using VPN, which is good. Not so good is to use Fritz!Box because the hardware is very weak and creating a secure VPN IPsec connection is only possible with much limitations. Nevertheless, some people still want to do it.
I tried to do it and was quite successful. The most tricky part is to find out what is going wrong when something is going wrong. There is not much logging that can be used for debugging, so it rather a lot of try and error until you finally get it right.
To share my configuration I created a wiki page with the configuration file that needs to be loaded into the router and the configuration that is necessary on the IPFire site. Please feel free to add the experience with your version of Fritz!Box and complete the guide where ever you think there is something else needs to be said.
I would also appreciate if you all would start collecting more information about how to connect IPFire with an other solution via VPN.