Review on CableDeconn Aluminum Multi-Function Thunderbolt Mini Displayport 1.2 to HDMI 4K & VGA Converter Adapter Cable for Apple MacBook Pro, Air, iMac, Surface Pro 2 3 4, Mini DP to HDTV Eyefinity VGA Adapter by Jesse Stewart

It worked fine right off my surface. However, I really wanted it to work from my Surface Dock. Microsoft doesn't say anything in the product information, but you might find on the support forums that they recommend an active adapter. It didn't work at first so I tried two active adapters but they didn't work either. After a lot of fiddling around (mainly with the Surface Dock, but I think this adapter also had some switching issues), I finally figured it out. where everything works when I sign in to surface AND turn on the monitor I want to use before I connect. But as long as I do that, everything works great. I actually have two monitors connected (one HDMI and one VGA), but I only turn on one at a time and it works as it should.