I have a customer with a Mac Book Pro. On two separate Netgear "router/hub/Wireless Access Points", after changing the wireless channel, about five minutes later the (radio strength) power levels drops from the max of five bars to two. Is the Mac Book Pro telling the router to do this? Is there some feedback mechanize in play to keep your signal from going down the street?
The customer also has an iPad and an Android phone on the network.
I don't know about Netgear, but there is no mechanism with which *our* APs will reduce our transmit power based upon what the client tells us (per se.) So I really can't guess what's going on. (The converse is not true, btw - there *are* protocols by which our APs may tell clients to change their transmit power.)
Let's say that you were to install WiFi Analyzer or similar on your Android phone, and put the Android phone next to your Mac, and lock the Android onto the AP of interest ("Signal Meter"). Then do your thing with the Mac. Do find that, at the time when the Mac reports a drop from five bars to two, the Signal Meter RSSI also drops?
The bars drop on all three devices (Mac Book Pro, Android, iPad). The customer has a fancy app on the android that shows strength of everyone around you.
My first thought was a feedback mechanism like that used on cell phones.
In the mean time I have found this in Netgear's manual:
(Optional) Clear the Enable 20/40 MHz Coexistence check box to increase the wireless speed to the maximum supported speed. By default, 20/40 MHz coexistence is enabled to prevent interference between wireless network in your environment at the expense of the wireless speed. If there are no other wireless networks in your environments, you can clear the Enable 20/40 MHz Coexistence check box.
Hmmmm. I am thinking that reading between the lines, if the router see a lot of other APs nearby, that it reduces its power to assist with congestion. And this customer has about 11 AP's showing up from his neighbors as he lives in a crowded community.
And, both routers were Netgear. And this is the most congestion I have seen with a Netgear router. (I have seen worse at an apartment complex with another router.)