GFI LanGuard displays the following error when scanning macOS computers:
The SSH connection failed with error 'Error connecting to SSH: 10061'
The SSH error 10061 meaning is "Connection refused". Most commonly this is caused by the SSH daemon not running (it is disabled in the macOS by default), an application (often firewall) blocking the connection, or an incorrect port being used.
Go through the Requirements to Scan and Patch mac OS Computers and check each of them. If the SSH port has been changed for security reasons, this can be addressed from the LanGuard console and is covered by the above article as well.