Connected the Surface 3 to the Microsoft Wireless display adapter, which uses Miracast, and discovered that it displays at a very low resolution (1366 x 768) on my HP EliteDisplay S240ml. Found out that others are having the problem, and turns out to be some type of conflict with Bluetooth. Turn bluetooth off and I can then get 1920 x 1080 display.

According to the support thread, the issue has to do with the latest Intel video driver for the Surface that for some reason is dropping resolution down to 1366 x 768 whenever it detects a bluetooth device other than the Surface Pen is connected.

The solution is to either turn bluetooth off or not use any devices other than the Surface Pen.

I can report that any time I connect a bluetooth device, or even turn it on or off, the wireless display disconnects. What this means to me is that for now I cannot use the Logitech k480 keyboard with the Surface if I want to connect the Surface to my monitor via the wireless adapter.

My workaround is to use the Logitech mouse and keyboard that connects via a USB dongle with the Surface. The result is that I have keyboard, video, and mouse all wireless attached to the Surface even if to do so requires a little work on my part to plug in the USB dongle.

An interesting side note. If you turn off bluetooth you can still use the Surface Pen with the Surface. I imagine bluetooth only needs to be on for the initial pairing. UPDATE: I discovered that the top button on the Pen uses bluetooth. If bluetooth is turned of the top button on the Pen does not work.

One more issue, there doesn't appear to be a fast way to make the Miracast connection from the Surface. The Windows key+P combination to project does not provide an option for wireless display; It should. The fastest approach is to go to the Start Screen and start typing wireless, which will bring up a search box of all wireless items on the Surface, including connect to wireless display.