Over the last little bit, I have had random issues with latency and throughput in specific areas both at work and at home with wireless. Mostly since I'm on the move it's been via my iPhone, but could also be noticed on iPads, the Surface and all other devices. Only difference being is to what level there was degradation.
Initially when I'm relatively close to the AP, lets say 100ft, minor obstructions I had very little issue what so ever. However, if there was the same distance with obstructions, or slightly longer distances all the devices would show a good signal strength. Percentage wise, around 35%, and dBm wise about 14-18 dBm. Now I know those are on the weaker side of the spectrum, but they are still usable. From a speed standpoint during initially installation I would still see 100Mbps + bi-directionally even with that signal strength. My latency would be about 7-10ms vice the normal 2ms at that strength but more than manageable.
As for my set up. It's identical between work and home, only difference being quantity and internet speed. Both networks are fronted by a Merkai MX-100, Meraki Switches, and MR-34 APs. That being said it's quality equipment that has always performed well for me. After some googling, more so about the iPhone and 802.11ac issues, I found a lot of people complaining about the 80Mhz configuration and the iPhone. That being said I wasn't seeing the same issues they were. For the most part they were having speed issues regardless of where they were in relationship to the AP. Mine were specific to the outer ring of the range. None the less, I figured I'd give playing with my settings to see what occurred.
Before I get into the settings, I will say that on the Meraki's, specifically when you go to my.Meraki.com when connected to an AP when you are set at 20Mhz = top speed of 400Mbps, 40Mhz 600Mbps and 80Mhz of 800Mbps. This maybe important to some depending on their internet speeds, and what they may be doing across the LAN.
To alter the settings on the Meraki, you need to go to your dashboard, Wireless, Radio Settings to alter the settings for your APs in the network.
As I mentioned earlier, I had been googling the issue specifically with the iPhone so I used some of the details there as my baseline. I started close to my AP and ran a speed test both on my iPhone and Surface and set a baseline of what I expected my AP Performance to be. I then went to the "problem locations" and recorded the bandwidth when things were performing optimally. Was getting about 125Mbps bi-directionally there as well.
I really didn't want to go down to 20Mhz as I had read on some of the articles with regards to the iPhone issues. However, the Meraki doesn't offer an "Auto" setting like some other 802.11ac routers do. I then tested at both 20Mhz, 40Mhz to see how the performance was. The performance at the 40Mhz range was equal to my previous tests. Even when running multiple simultaneous speed tests all the devices performed the same, and on par with what I was seeing at the 80Mhz range.
Thus my thought is if you are running a high concentration of Apple Devices, go ahead and drop your 5Ghz band to 40Mhz and call it a day. Second to that put in a feature request with Meraki (or your vendor) to support the "Auto" functionality.