Two EC2 Windows instances in the same VPC fail to access a shared folder via SMB. Security groups and NACLs are open, Windows Firewall is disabled, but net use reports error 1792, and packet capture shows STATUS_NETLOGON_NOT_STARTED. The root cause is not VPC networking — security software is intercepting the SMB authentication flow.

After adding NTFS security permissions to an FSx ONTAP SMB share, users are still unable to access it. The key to this issue is: the effective Windows SMB permission is the intersection of share permissions and NTFS permissions, and Kerberos tickets do not automatically refresh group membership while the user remains logged in.