I also encounter problem with connecting to my 42LB631 after upgrading to Windows 10 from 8.1.
I updated all Network, Adaptor display driver to the latest one. When I connect my laptop from Action Center, it announces Connected but the TV screen is black and after few seconds it shows an error message of "MIRRORING ERROR, we can't mirror your device screen connected via Miracast. Check you device"
In previous Window 8.1, it worked very well.
I'm waiting for a solution maybe from Intel, Microsoft or LG.
