If I'm like 5 feet from the AP I'll see about 600Mbps on 2x2 802.11AC, that's about as good as it's going to get because the link speed is only 866Mbps, and you're never going to get close to that with actual transfer speeds due to overhead.
Speed drops off very rapidly with range on 5GHz, so across the room it'll be down to 300Mbps or so already.