This information is stored in the tsyserrors database table. I've included a sample report below, which you can add to your installation by following
these instructions.
You can force Lansweeper to create assets for all pingable IP addresses by the way, even if the device has no open ports. To do so, tick the Save Pinged IP checkbox for your ranges under Configuration\Scanning Methods. You'll get basic asset pages listing the device IP. In order for Lansweeper to retrieve any device data, one of the protocols mentioned
here will need to be enabled on the device.
Select Top 1000000 tsyserrortype.Errorname As Type,
tsyserrors.Errormsg As Message,
tsyserrors.Scanserver,
tsyserrors.Added
From tsyserrors
Inner Join tsyserrortype On tsyserrortype.ErrorType = tsyserrors.Errortype
Where tsyserrors.Errormsg Like '%no open ports%'
Order By tsyserrors.Added Desc