After the Windows 2008 R2 64 bit server got below 2 updates a network share is no longer available. And trying to remap it with correct credentials (that work on a Windows 8.1 64 bit) gives this error: "System error 86 has occurred. The specified network password is not correct."
Local Policies -> Security Options -> Network Security: LAN Manager Authentication Levelis already set to "LM and NTLM - use NTLMV2 session security if negotiated"
In fact this is how it was working earlier. And it hasn't been changed.
Below 2 updates were installed in past few days:
Definition Update for Microsoft Endpoint Protection - KB2461484 (Definition 1.185.3528.0)
Update for Windows (KB974405)