IPad Air 2: network latency higher than expected

I have both an iPhone 6 and iPad Air 2 that are both using the latest iOS 9 release. I've run internet speed tests on both. The average ping time on the iPhone is about 15ms, and on the iPad about 37ms. Doesn't seem the right way around to me. I've tried forgetting the wifi network, reboots, and network settings reset on the iPad. None of those seem to make any difference.

Any ideas of what else I might do to get the network latency down on my iPad?

Thanks!