This sounds quite similiar. Perhaps both threads should be merged.
Have you tried to set the max. smb version setting to smb3 on the Syno?
On the Syno: Control Panel → File Services → SMB → Advanced Settings
This sounds quite similiar. Perhaps both threads should be merged.
Have you tried to set the max. smb version setting to smb3 on the Syno?
On the Syno: Control Panel → File Services → SMB → Advanced Settings