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

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

Since November 20, 2013 I have problems with the internet acces 2 with Iceweasel and Firefox 24.
Websites and are not displayed - nothing happens after enter.
But 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?