I have had this issue plaguing my help desk for a while now without being able to find the root cause. Eventually, they convinced me it wasn’t the two particular MFP’s having issues (I have dozens deployed with no issues) and I started digging. I came across the issues with KB3161949 while I was digging and saw that these two MFP’s hadn’t worked since I installed that update (let’s just make it easy and say until I came around WU’s were never done on servers). Anywho, I just followed the instructions from the technet article, bounced the box, and when we tested the next morning it was right as rain.
Value Name: AllowNBToInternet
Default value of the flag: 0