sdykes:  TimA has correctly identified the problem just really want to know why it occurs??

I would assume the router can't cope with the traffic. I was getting ~50Mbps wifi throughput over a ~60Mbps VDSL connection, but that was using an Asus RT-AC66U as the wifi access point, with a Draytek DV130 bridged as the VDSL modem. There's no inherent "Wifi -> VDSL = slow". Using the same RT-AC66U, I can now get ~80Mbps throughput via Wifi over 100Mbps UFB.

I have not been able to find a logical reason why this happens. I truly have no way of putting 1 and 2 together in my head to make myself understand why its all of a sudden slower for local and WAN transfer. All i know is a couple of things the tier 3 guys said and my real world tests at multiple sites. My buddy get 160-180Mbp/s WAN transfer to 200Mbp/s UFB.