The direct print service produces a collection of log files. These files are usually used for debugging and analyzing the operation of the service.
Log files are stored in the following folder:
C:\ProgramData\ForNAV\Direct Print\Logs
You can get the log for a specific connection if you right-click the environment and choose View Log.
If you need support with direct print, it is often helpful to zip and send the log files together with the problem description.