Why is LUN Backup unable to back up to a Windows 10 or Windows Server 2016 shared folder?
Storage & Snapshots > LUN Backup requires SMBv1. If SMBv1 is not supported by the backup remote host, LUN Backup will display an error when testing the backup shared folder.
According to Microsoft, SMBv1 is no longer installed by default in Windows 10 and Windows Server 2016. To work around this problem, reinstall SMBv1 in Windows.
If you are using QTS 4.3.5 or later, you must also ensure that QTS supports SMBv1. Go to Control Panel > Network & File Services > Win/Mac/NFS > Microsoft Networking > Advanced Options > Supported SMB versions and verify that “SMB 1” is selected under Lowest SMB version.