I have a SY NUC, but it doesn't have this device!!
First of all, if you haven't already, I would install the Chipset Device Software INF Update package. Here is a link to this package: https://downloadcenter.intel.com/download/26804/Intel-Chipset-Device-Software-for-NUC6i3SY-NUC6i5SY-....
I would also recommend that, if you haven't already, you should install the Serial IO driver. Here is a link to this package: https://downloadcenter.intel.com/download/25398/Intel-Serial-IO-Driver-for-NUC6i3SY-NUC6i5SY.
Finally, I am wondering if you have a unit that has had one of the fancy Near Field Communications (NFC) lids or something similar installed into it. Here is the link to the driver package for NFC: https://downloadcenter.intel.com/download/25399/Near-Field-Communication-NFC-GPIO-Driver-for-Windows....
Hope this helps,
I Used Drivers from HP to get rid of the yellow /!\ on PCI Data Acquisition and Signal Processing Controller on my Sumvision Cyclone Mini PC 2
Run the exe then didn't use HPsetup or setup, just did Right Click on PCI Data Acquisition and Signal Processing Controller in Dev Mgr and browsed my computer for drivers (with search subfolders ticked) and pointed it to SWSetup\sp91763 folder
This should fix the missing Intel(R) Serial I/O UART Driver iauarte.sys