I work in an office with about 15 employees we have a wireless network that consists of one R500 and one ZD 1200. I used the zone planner to set the network up and it recommended one AP. So I put the AP in the location specified. Now the issue is one office is down the hall about 100 Ft or so and it is Sensurround by concrete walls. Now there are two devices in this room one is Chrome cast works fine no issues. The other is an IPhone 6 Plus. The IPhone is having all kinds of issues where it will not stay connected to the network It drops out all together. I have taken multiple devices into this "Dungeon" as we call it here and have had a perfectly fine signal no drop in service or anything along these lines. I checked the log on the ZD and it does not show any kind of major interference. I have ruled out the issue being on the network and believe it to be with the device but before I announce this to my boss who does not believe it is his phone I decided I would get on here and see if I can get some more ideas for troubleshooting or opinions.
Do you have the same SSID on both 2.4GHz and 5Ghz radios? I wonder if the Chromecast is getting a 2.4Ghz connection and the iPhone is using 5Ghz, which would have a lot worse reception under those conditions. Might also make sure said iPhone user doesn't have a crazy case that's attenuating his signal. I'd put an AP that room 😉 Why have a controller with a single AP, anyway? 😄
Apple devices do have a tendency to prefer connection to 5GHz networks, as your 'dungeon' is encased in concrete and is 100ft from the AP its safe to say that 5GHz will be less than optimal. You could enable an additional SSID only on 2.4GHz and test again to see if that makes any difference. Also you have to consider every client device will see signal levels differently.