I spent some time addressing WiFi issues in an apartment of a large complex. The hunch was it might be related to congestion, but the shock came when iStumbler was used to determine how congested it actually was.
Almost all the access points were running on 2.4 GHz.
And almost all of those were provided by AT&T (i.e. SSIDs of ATT, 2WIRE, etc).
Sparing the long story, a piggy backed router on the 5 GHz band increased Internet speeds by 7 times on the opposite end of the apartment and 2 times near the router – nearly a 15 Mbps increase! Note: the original 2.4 Ghz channel on the AT&T router was disabled to free up some unnecessary congestion on the spectrum.
It was an easy fix for this individual but my major concern remains. AT&T is over-saturating the 2.4 Ghz airwaves surrounding the building, but yet they continue to add customers without addressing the issue. An ISP clearly should understand this type of behavior is not going to provide an acceptable level of service to customers.
At minimum they should be supplying routers capable of 2.4 GHz and 5 Ghz so the appropriate spectrum can be chosen to minimize congestion, perhaps assigned by floor.
More appropriately though, AT&T should be working directly with the building to supply adequate Internet service. The customers are clearly there and already paying for it.