Instead of purchasing an add on USB wifi device just use a compatible Wifi ac router. Many modern Wifi 802.11ac routers can be turned into bridged mode or as access points using the router settings. You can use the 1Gb Ethernet port on the Mini to connect a Cat7 Ethernet interconnect cable to a 1Gb Ethernet port on the compatible Wifi ac router and set that router to bridge or access point mode in order to connect via 5Ghz ac wireless to your main 802.11ac Wifi router. This should give you much improved wireless range and optimal transfer speeds compared to when you use the 2012 Mini's built in Wifi.