Receive this error when opening explorer in SharePoint 2013 library:
We're having a problem opening this location in File Explorer. Add this web site to your Trusted Sites list and try again.
This error happens on the Windows 8.1 client and Windows Server 2012 R2.
Using Windows 8.1 with all updates
Tried IE 11 64bit and 32 bit same result
Server is 2012 R2 datacenter with all updates
SharePoint 2013 foundation with SQL express (out of the box setup)
Web client installed and running on both Windows 8.1 and Server 2012 R2
Added the site to both server and client in the trusted site area of IE
Please help with any other ideas.