I can ad myself to those who have been disappointed with updating to windows 8.1. It took all day to download on the day of release and then reinstalling my apps. During the update , internet connection was fine (very slow) but after it completed the browser start for 5 minutes and then " this page can not be displayed". I have to restart after that... I went through my modem setting (new) every thing is fine.. was working fine on windows 8 so why it doesn't work on 8.1 ? Microsoft community no help either as they asked me to change or update drives which are already up to date.. If you are having this problem , just go back to older system til MS come back with new sp2.. Care
Perhaps you have DNS issues, try adding Google dns to your lan setup (8.8.8.8/8.8.4.4) and see if that helps, also try restarting your router.