This is not a windows issue.  I have another Dell with Windows 7 which never looses WiFi connection.  I have 8 other devices (2 Dells, iPad, Android, Nest) which never loose the WiFi connection.  But the Dell Ultrabook has some bad hardware or driver.  I loose connectivity for 1-2 minutes and then recover.    I hope Dell realizes this issue and provide a fix and not send us on a wild goose chase with microsoft.
The laptop was working fine the first few months and then it decided to just suddenly stopped connecting to wifi. I mean it connects to wifi but there's always an exclamation mark on the wifi icon and the connection is always limited or no internet access while everyone else's laptop and my iPad and iPhone have internet access connecting to the same SSID. So I have been using an external wifi card and it was fine. Until 2 weeks ago the external wifi card was having the same problem (limited or no internet access). I googled and followed the suggestion of someone by choosing maximum performance for my wifi and networking cards at the power option. And then it worked again (without using the external wifi card). But now it's back to the old problem. I have tried updating my drivers, BIOS, and nothing works. I'm using Windows 7 Home Premium SP1, Avira antivirus (free version).
Dell Inspiron 14z Ultrabook wifi connectivity problem