I've been having the same problem with my Dell Latitude E6430.  I tried everything I found online with no luck.  I even applied all of the system updates that Dell rolled out this week (most dated 10/17/2013).  Nothing worked.  I found this today and it solved my problem (from [URL] Hi guys, i tried all the above methods but none of them worked for me. However i did find something that worked, which is to revert your network adapter driver back to an older version instead of the one installed by windows 8.1. You can do this by going to device manager, right click on your network adapter, go to update driver, then "browse my computer for driver software, then"let me pick from a list of...." , uncheck the "show compatible hardware" checkbox and finally select the older version of current driver (if you dont know which, just use trial and error). Hope this helps the rest who still have this problem.Cheers. The specific driver that worked for my Dell Latitude E6430 was the Broadcom 802.11n 5.100.245.200 (dated 3/14/2012).
After a recent clean install of Windows 8.1 on my Latitude E6430, I can no longer access my work wireless network with utilizes 802.1x and Cisco wireless controllers. This is using the RTM version of Windows 8.1. Windows 8 and the customer preview of 8.1 worked without any problems.  Windows installed the Broadcom 802.11n Network Adapter upon installation. When that didn't work, I updated the driver using the Dell support site and installed the Dell Wireless 1504 802.11b/g/n (2.4GHz) drivers.  Both drivers result in the same thing: I get connected with limited connectivity and usually a self-assigned IP.  The wireless works fine on home networks using WPA2.  Any ideas or troubleshooting suggestions?
Windows 8.1 Latitude E6430 Wireless Issues