This is a bit of a tangent, but is Wi-Fi becoming more finicky in general, perhaps due to spectrum congestion? I find I somewhat frequently have Wi-Fi related problems of the sort you're describing on a variety of devices. It seems Wi-Fi from about 5 years ago was perhaps slower but more reliable. Am I just imagining this?
I had to reboot the access point in the end so perhaps it wasn't an Apple problem. Yet no other devices were having issues and I've not had a problem with it since it's been running Windows.