I regularly connect my aging Surface Pro 3 to various external monitors via the displayport. I am running Windows 10. Last night this worked fine on one monitor; this morning it did not work on another. I have tried two different monitors and two different cables without success. There have been no hardware or software changes overnight, other than the switch from one regular monitor to another. The only explanation I can think of for the overnight change is that the displayport jack has gone bad. Does anyone know of a way to test this hypothesis? Can anyone think of another reason why it would stop working overnight? One more clue: when I press Windows+P to project, it always defaults to the first option [PC Screen only], even when an external monitor is connected. I cannot get it to stay on the second option [Duplicate]. This suggests to me that the Surface is not detecting the external monitors.