@TCarbone, I have this exact same issue in the exact same scenario. Surface pro 3. Could you provide some insight on how exactly to update the Marvell Wifi Driver please? I downloaded the .CAB file from the Microsoft Update Library, and tried to run that CAB file using the Command Prompt, but the command prompt can't seem to recognize the file location. I am somewhat of a newbie for running drivers manually without any type of "engine" so any insight would be greatly appreciated. Also, I called Apple Support to open a ticket with them. The support specialist said this was the first call she received regarding the hotspot not working, so hopefully they start to receive more to make this a priority. 15.1 doesn't have a patch or fix either... Definitely frustrating.