Default gateway not available windows 8.1

all you have to do is to change your network adapter driver from "Broadcom 802.11n Natwork Adapter" to "Broadcom 802.11a Natwork Adapter" and your wifi will work properly.

below are the steps to change network adapter driver.

i have Lenovo Z580 

solution worked for me was...

1>open device manager

2>expand network adapters

3>double click on Broadcom 802.11a network Adapter (i.e open your wifi N/W adapter properties) 

(Nore:- you might have Broadcom 802.11n network Adapter than select that)

4>select driver tab n click on update driver...

5>select Browse my computer for driver

6>click on let me pic from list of device....

7>unchack show compatibale hardware

8> now from the manufacturer window select Broadcom and from the Network Adapter list select the the driver having name Broadcom 802.11a Network Adapter and re connect your wifi..

Note  that u have to select 802.11a by default it was 802.11n...

if still have problem try another driver from list any one of tham will defiantly work..