Controllerless Networks

I have an instant cluster consisting of IAP-225's running 6.4.2.0-4.1.1.1_46936 .  The issue that I am having is that my clients wont connect at the expected speeds even when standing next to the AP.  Signal strength is great for the client.  I am not sure what is causing the rate to be so slow. Please see the attached screen shot from my mac. This is the highest rate I have seen and I am only 5 feet from the AP. Most of the time my 802.11ac clients are running at sub 500mbps speeds.  I have another instant cluster at another location and the clients are seeing consistant speeds over 1Gbps.  

The speed can be a function of contention.  If there are more users contending for the medium, or there is some interference, clients will de-rate and negotiate at lower speeds.   Getting rates at over 1 gig in a half-duplex medium like wireless is a gift and not a given.  It is tougher still to maintain that rate, period.

Here is a screen shot from the IAP. Noise doesn't seem to be an issue for me. Could it be the Min/Max rates I have set for the SSID?  

The rates do not matter.  What is the model of that device?  It could also be limted by the number of spatial streams it is capable of.  http://chimera.labs.oreilly.com/books/1234000001739/ch02.html#comparison_of_ac_data_rates_to_other__phys

Clients only acheive maximum rates under perfect conditions, short distances and virtually clean environments.

Device is IAP-225. It only has 5 clients connected and doesnt seem to have much noise/interference.  Could it be because 80MHz is disabled?  Would it hurt anything to enable it?

Please take a look at the chart at the link I posted above to see what rates are possible with what AP/Client settings to determine that.

Resolved. Enabled 80MHz and I am getting +1Gbps speed for AC clients. Thanks for the help.