My wireless speed on my laptop is 70Mbps using the 5Ghz wireless then drops to anything from 7-16Mbps over anywhere from an hour to a day. When it drops down in speed it never goes back up. Ever.
What I've tried.
Smart Setup is disabled.
Gave a different SSID to 2.5Ghz wireless from the 5 GHz wireless.
Set to channel 36 for 5GHz and used WifiInfoView to see if anyone else was using channel 36 - no one is.
Reboot the router and got 70Mbps speed (tested on speedtest.net) but then after a bit it drops speed again.
If I change the channel from 36 to 40 (no other wireless on either) the speed goes back up. If I reboot the router the speed goes back up but always drops down again.
Obviously this drives me crazy.
Another weird thing. I use Bonjour to connect from my laptop to appletv over wireless from iTunes. appletv is wired directly to the router, so the issue is over 5Ghz wireless to the router. It shows the appletv connection in itunes then it drops. My laptop is using the 5Ghz wireless. If I reboot the router or change the channel of the 5Ghz wireless it works again. Then drops out just like the speed.