The 1 Gigabit/Second Speed Limit
THIS IS FUNDAMENTALLY SIGNIFICANT
The first rule of 802.11ac and 802.11ad is: You can't move data across your Ethernet network at speeds greater than 1 Gbps.
When two wireless devices communicate through a single 802.11ac or 802.11ad access point they'll be limited only by their own capabilities. When a wireless device communicates through an access point to a destination that's reached across the wired Ethernet infrastructure the bottleneck is going to be the Ethernet itself. Even the best Category 6e shielded cable only provides Gigabit Ethernet speeds (1000 Mbps) - significantly less than the close to 7 Gbps specified by 802.11ac and 802.11ad.