Controllerless Networks

I've started testing new IAP325's recently with code 6.4.4.3-4.2.2.0_53034, and run into a performance issue where network throughput of the Iphone6 (IOS9.2) is very slow. I've tried deslecting all channel in the 5Ghz, except one (36) and tried with no luck. Then I did the same with channels 40, 44 and 48 but still no luck. Also changing the minimum radio power from 3 to 6, 9 until 18 didn't make any difference. Disabling client match, client aware, scanning or 80Mhz support does not change the performance.

In the end, when disabling VHT on the Virtual Controller, the performance improved big time! When re-enabling VHT performance dropped down back to terribly slow. When checking the monitoring view, I noticed a lot of 'retries in' regarding frames (fps).

When using a Ipad 4 (AN and IOS9.2), Ipad Air2 (AC and IOS9.2) and Windows Lumia 950 (AC and OS10.0.10586.29), network performance is excellent and similar to Iphone6 without VHT enabled on the VC.

As the Iphone6 also seems to be experiencing this issue with the AP325 (http://community.arubanetworks.com/t5/Community-Feedback/iPhone6-AND-VHT/td-p/254499), I was wondering if anyone else also has expeience this issue, with other AP models and/or software codes.

Thanks!

Which direction are the retries high?  From or To client?

While a little dated, i ran into a simlar issue with some iPad Pro devices connecting to amn IAP-325 cluster running v6.4.4.4-4.2.3.2. More or less the same, all other devices seemed to work fine but the iPad Pro's were connecting using thier a radios and VHT. Lots of interface drops and had the appearance of a coveage issue. Just as you described, I had to disable wide bands (40 or 80Mhz) and drop back to 20Mhz channels to get things snmoothed out. This was even after upgrading the iPads to IOS 10. 

Seems there is someting "funny" with the way Apple devices are trying to connect / make use of VHT.

There is not enough information to know what is happening, but If you are not using DFS channels, by default 80 mhz channels and 40 mhz channels have fewer non-overlapping channels which creates contention, which lowers performance.