Internet access 1 Provider: Vodafone easybox 803
Internet access 2 Provider: HLkomm Fritzbox 7390

Knoppix 7.2 from USB-Stick
Partition mounted read-only
roughly same PC's on both access points

Webbrowser:
Iceweasel, Konqueror, Chromium (Knoppix 7.2)
Firefox 24
Firefox 25.1
Adblock Plus 2.2.4, NoScript 2.6.6.1 (Scripts permitted)

Since November 20, 2013 I have problems with the internet acces 2 with Iceweasel and Firefox 24.
Websites google.de and heise.de are not displayed - nothing happens after enter.
But spiegel.de and other websites are correct shown.
With Konqueror, Chromium and Firefox 25.1 all sites are o.k.

Internet access 1 works still correctly also by google and heise with all browsers.

Is there an explanation for this?

Thanks
Moritz