今天心血来潮把家里的两台笔记本都升级到了win8.1。
升级很方便，在app store里边点upgrade，等着下载完成后自动安装，再重启后做一下简单的设置就可以了。但是有一台Dell N4020升级后wifi就怎么也连不上了，显示连接受限。不知道发布之前是怎么测的。前两周听说Ivan的笔记本升级也出现问题了，直接挂掉，不得不重装。看来win8.1升级的问题不少。
share一下解决方案吧, copy from http://superuser.com/questions/665402/windows-8-1-killed-notebooks-wifi
After further research i discovered a fix that worked for my particular device.
I followed these steps:
Open Device Manager (search Windows Help if you don’t know what this is)
Select ‘Network adaptors’ and then open (double-click) Broadcom 802.11n Network Adaptor
Go to the Driver tab and click the Update Driver… button
Select ‘Browse my computer for driver software’
Select ‘Let me pick from a list of device drivers on my computer’
Select the “Broadcom 802.11n Network Adapter (Broadcom)” entry from the list, and click
I used the Broadcom 802.11n Adapter version 5. Next restart and test.
Note: You must disable compatible hardware checkbox to find the previous versions of the driver
This solution uses the driver that was working before installing windows 8.1
UPDATE: After further testing i discovered that the broadcom 802.11n network adapter was actually limiting my connection speed. I am now using broadcom multiband network adapter with full speed