I'll explain what's wrong here, I have a Samsung S3 i9300 with Android 4.3.1 (SlimBean) and everything works fine. Only when I turn on WiFi (tried several), my internet acces is limited to the google site, and some apps like Facebook and Whatsapp. But when I try to navigate to other websites, I recieve a -Not found- error.
So it seems like technically everything is ok (otherwise I also couldn't open google in my browser). Other devices connected to the same network do not have this issue. I tried to change DNS settings (e.g. 126.96.36.199), but this is not possible in 4.3.1 as far as I can see.
Any suggestions are welcome!