Unsurprisingly, AVM is now trying to claim their legal action is not related to any GPL violation. This couldn't be further from the truth.
In both the court hearings (in two independent cases), AVM has repeatedly declined to make a clear statement that the modification and installation of modified version of the GPL-Licensed parts (like Linux) is acceptable to them.
We have raised this question in front of court and out of court, and AVM was not willing to make such a declaration. If they had, I don't think I would have had much reason to join the lawsuit on the side of the defendant.
I have no connection to Cybits (the defendant). There has never been any business or other relationship to them, and they have not been involved in funding my legal expenses. To be honest, I don't even care about child filtering software in general, no matter from which vendor.
But I do care about the GPL, and the freedoms it grants. The GPL is intended to allow any third party to modify, recompile, re-install and run modified versions of the respective GPL licensed program. Any court order / verdict / judgement that tries to undermine this freedom is a substantial danger to the Free Software movement - and as such I will do what I can to prevent it.
AVM has stated in front of the court that AVM releases the source code compliant with the GPL, anyone can download, compile and use it - just not on OUR hardware. There you can clearly see their attitude: They see the FritzBox as their hardware. Last time I checked, the unit is not rented by AVM, but is legally sold to the customer. It is his decision to do with it what he wants. Under the terms of the GPL, it is his decision to install whatever software on the hardware, including modified versions of the GPL licensed Linux kernel.
Just imagine a world, where you buy a Laptop from HP, with Windows pre-installed. Now further imagine that there is a third-party software vendor (e.g. Canonical with its Ubuntu). Now imagine that HP was suing Canonical for offering different software that runs on their hardware. This is the kind of analogy that you need to think about.
I don't think AVM is truly understanding the daemons they are calling here. If they actually manage to get a finally awarded judgement that deprives third parties of their rights under the GPL, AVM will have violated the GPL, specifically clause 6: You may not impose any further restrictions on the recipients' exercise of the rights granted herein. And what would that mean? That the GPLv2 is revoked and AVM looses the right to use the GPLv2 licensed software they use in the product.