I guess I"ll put this here in case it helps any future searchers.
I couldn't connect to 802.11n 5 ghz at home with my Surface Pro 3.
I have a DD-WRT router at home..
I finally ran across a link with for DD-WRT with the Qualcomm Atheros chipset best practices
http://www.dd-wrt.com/wiki/index.php/QCA_wireless_settings
It said that when wireless mode is set to 'N only' with this software, it is frequently broken. So I changed it back to mixed, and could immediately connect.
I changed my channel width off 20 Mhz to 40 Mhz (I'd only changed that to 20 as part of troubleshooting recommented here), and got reasonable speed.
So turns out it was me and not the Surface also