I am having same problem with unknown phone showing up on my network but router does not show it is accessing my network. Still working on that.
Anyway I have a Lenovo computer and when I upgraded to windows 8.1 I lost wireless connections due to the Realtek RTL8188E wireless driver adapter. In the device manager look for the wireless adapter and select properties to see if you are getting device
not working properly and an error code.
If so This is what fixed mine. Found on the Lenovo community site. Instructions below:
Driver Installation Instructions for the Realtek RTL8188E Wireless Device
Go to this website:
http://devid.info/58248
And click on the TINY link that says, "58248_wl_139h_2007.2.0706.2012_w800.zip" (31.9 Mb) and download the
zip fle. Extract the .zip and place that folder (58248_wl_139h_2007.2.0706.2012_w800) into your Drivers folder in Local Disk C. (This is the RTL8188E driver which is extracted but not installed)
After placing extracted files (58248_wl_139h_2007.2.0706.2012_w800) in the drivers folder:
1 From the DEVICE MANAGER, find the Realtek RTL8188E Wireless Device and click to "Update Driver".
2 Then click "Browse My Computer for driver software"
3 Then click "Let me pick on a list of device drivers on my computer"
4 Then click on "Have Disk" button and browse to netrtwlane.inf which is slightly buried in the 58248_wl_139h_2007.2.0706.2012_w800 folder.
PATH: 58248_wl_139h_2007.2.0706.2012_w800 -> RTWLANE_Driver -> Win8X64 -> netrtwlane.inf
5 Once netrtwlane.inf is selected, click OK and click NEXT to continue.
6 INSTALLED!!!!!!!!!!!!!!!!
7 DON'T TOUCH THE DRIVER BECAUSE MICROSOFT STILL SEES THE ORIGINALL DRIVER AS THE LATEST.
Good luck!!