Any plans for SMB v3 or updated v2 support so 3rd party signing does not need to be disabled for Windows 8.1 machines?
This problem is caused by the “Secure Negotiate” feature that was added to SMB 3.0 for Windows Server 2012 and Windows 8. This feature depends upon the correct signing of error responses by all SMBv2 servers, including servers that support only protocol versions 2.0 and 2.1. Some third-party file servers do not return a signed error response. Therefore, the connection fails.
http://support.microsoft.com/kb/2686098 as mentioned here: http://forum.mikrotik.com/t/rb951ui-smb-not-share/77304/1