We faced share access problems between client and server Windows 10/Windows 2012 R2.
Network access problem was solved utilizing this powershell command on Server 2012 R2 and client Windows 10.
Set-SmbServerConfiguration -EnableSMB2Protocol $false
More details on this Microsoft support article 2696547
How to enable and disable SMBv1, SMBv2, and SMBv3 in Windows Vista, Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows 8, and Windows Server 2012