Webseite nicht Verfügbar / Website not avaible FP1

It’s the web browser. It is outdated and should not be used anymore (in fact it has been outdated for about 3 years or more). See here:

In short: Install a browser from the suggestions there. Or install the new community version of Android Kitkat with the latest security patches: Android KitKat (4.4.4) for FP1