FIX: WebClient Service Missing in Server 2016/2012 (Fix Error 0x80070043: Windows cannot access the SharePoint site).
The WebClient service, allows Windows programs to create, access and modify Internet-based files from File Explorer. For example, if you want to access WebDav shares, or files hosted on SharePoint Online, by using the Windows Explorer or other programs, the WebClient service is required and must be running on your system.