Hi Daniela,
It looks like there is something in the network which is blocking the device to get connected. So I would suggest you to go through the article and check for the exact issue.
Why can’t I connect to a network?
http://windows.microsoft.com/en-us/windows-8/cant-connect-to-a-network
Why can’t I find a wireless network?
http://windows.microsoft.com/en-us/windows-8/cant-find-wireless-network
If you have any third party software installed on the computer, you can try disabling the anti-virus software and check.
Important Note: Antivirus software can help protect your computer against viruses and other security threats. In most cases, you shouldn't disable your antivirus software. If you have to temporarily disable it to install other software, you should re-enable it as soon as you're done. If you're connected to the Internet or a network while your antivirus software is disabled, your computer is vulnerable to attacks.
Reference:
Wired and wireless network problems
Do let us know about the results. We would be happy to help you further.