When applying a firmware update to your Tacx Neo, you may see a “phantom” device listed on the devices tab of the Tacx Utility App.
You should only see this mysterious “device” if you apply an update and then switch to the Devices view in the Tacx Utility App. It is normal, and is not a problem.
DFU means Device Firmware Update. This is the virtual device that the firmware bootloader connects to when applying firmware updates to your Neo (and other devices that use the Nordic Semiconductor processor). It will go away after you exit the app after the update.