I have my primary AirPort Extreme (5th Gen) hooked up directly to my modem (Motorola Surfboard) and I get 50+ Mbps on my IMac via Ethernet. Wi-Fi I only get 25-35 Mbps in the next room and 10-15 Mbps down stairs. I figured this was due to good house insulation. I set up a 2nd AP Extreme (4th Gen) down stairs via Ethernet over power line. Only getting 25 Mbps by Wi-Fi down stairs also. What gives?? Why are my Wi-Fi speeds so slow?