Hello! I have been looking all over internet to find a solution to my problem, HOPEFULLLLY actually talking about it will help. I have ISP 100mbps and it's very stable, can't complain, yet my speedtest.net results show download speed 45 to 50mbps download and above 50mbps upload. I called my ISP and a guy came with DELL laptop running Windows, for him it was 65mbps d/l and 89 u/l. OBVIOUSLY the problem is in my MACBOOK PRO RETINA 15" Early 2013 running on Software OS X 10.8.5. My Transmit rate is 73, MCS Index is 7 (numbers taken from cmd + wi-fi dropdown) and when i open wireless diagnostics (same dropdown) and go to utilities, under Info it says my channel width is 20 MHz but under Wi-Fi scan it says 40 MHz. I have read that transmit rate a.k.a Link Speed (in Network Utility) can go up to 72 mbps if using 20MHz and having one spatial stream (MCS = 7). Also I have read that all Macbooks internal wi-fi cards don't allow use of 40MHz channels. But it should allow more than 1 spatial stream, right? I have TP-Link 150 mbps Wireless N Router TL-WR740N. Help please. I've been spending way too much of my time trying to fix this.