So I've recently bought myself a used cMP 5,1 and completely love it, couldn't go back to my old i7 iMac The only thing that's not so nice is that my WiFi speeds are much much much slower. I used to get 140 Mbps on speedtest.net (I've got 200Mbps connection) and a Tx Rate of 180 Mbps. Now I'm getting a Tx Rate of 145 Mbps (which is decent) BUT the download speed is only 18-20 Mbps ??? This is quite bad and makes my NAS server quite a pain to work with. I've got no idea on what to do and I can't run an ethernet cable to this point in the house without tearing open half the walls in my house so thats not an option and powerlines don't really work this far either. Ow and btw the router is and Airport Extreme AC Hope someone can help !!