802.11ac.. increase availability by disabling MIMO?

[Just Someone YKnow]

We have a WLC 5520 running version 8.5 and 3802i radios. We can't afford any Prime management, I only have the WLC web GUI to manage it..

I want to make sure that there is always free channel space available for new clients. I do not care if AC MIMO is used at all, if using it will result in reduced client connectivity in a dense device environment.

It appears that by default the controller will try to run client connections as fast as possible wherever it can.  I have at times seen up to an 800 megabit client connection, established to a single device that doesn't actually have a need for more than about 10 megabit Internet connectivity.

It is unclear to me if it will try to continuously maintain this ultra-fast MIMO connection to a single client, even if it means that other clients just coming into the the airspace are denied access because all channels are already in use.

We kept having connectivity problems until I went into "802.11a > RRM > Dynamic Channel Assignment (DCA)" and changed the channel width from "Best" to "20 mhz". I no longer see the 800+ megabit connections, but people have stopped complaining their device can't connect.

Should I be changing the "802.11n/ac (5 GHz) Throughput" and force the disabling SS2 "0-9" / "0-8" and SS3 "0-9" / "0-8" to turn off MIMO and assure maximum client channel availability?

I have read that disabling the higher single channel connect speeds is actually worse for a network because faster speeds need less time to send, and so can pass through interference better. 

[Leo Laohoo]

Just set the channel width to 20- or 40 Mhz will do fine.

[patoberli]

As Leo states, don't disable those rates, just set DCA to 20 or 40 MHz. Also make sure you have enabled all allowed channels for your country. That will vastly increase the possible spectrum and lower the channel re-use.
Also, if a client uses 800 Mbps, then he needs it! The quicker the data transfer is done, the faster the airtime is freed for other users. So if you enable only very low data rates and the clients needs 10 minutes instead of 10 seconds for the same transfer, he actually saturates the air nearly 100% of the time for 10 minutes instead of 10 seconds (this theory is vastly simplified for this example).
Of course, if you have users that download non stop as much as they can, then this doesn't really free the airtime. In that case you have to work with (paper) policies where you forbid the use for certain usage scenarios... If that doesn't help, then the next step would be a web proxy.