We have had a similar issue with a couple of misconfigured sites.  Turned out to be the mtu setting on the path to the site from radius.  The isp’s kit was configured to a figure below 1473. The first packet would be returned by the radius server but the remaining packets of 1500 size would fail. A quick check is a mtupath tool.  Next time it’s happening try this from either end to confirm if this could be the cause. ... View more

This article may help it is a little old but does contain some of the Apple ecosystems roaming decisions.  What are the minimum data rates set for your aps?  You don’t have differing radio profiles for the different aps?   https://www.stevenjordan.net/2016/03/fix-iphone-wi-fi-problems-part-i.html?m=1   https://support.apple.com/en-gb/HT206207   There is also some tools that Apple offer to run some capturing from the devices.  There logs are pretty verbose but may help to capture what is prompting them to dissaccoiate. https://developer.apple.com/bug-reporting/profiles-and-logs/?name=Wi   found this on the ubiquiti forums as well, although old does seem to point to fast roaming. https://community.ui.com/questions/Intermittent-Connectivity-with-Apple-Devices-and-Fast-Roaming/f3755d0c-101c-4e16-bd04-71e28b49a22d?page=11 Rather than disabling the 802.11r and k/v settings try enabling them. I believe there is an adaptive mode as well.                  ... View more

It’s not something like a dhcp lease expiring? Any of 802.11r or k enabled on the ssid? Dfs event? Channels/power aren’t changing? ... View more

What wpa encryption mode is in use? Have seen apple devices struggle when wpa1 and wpa2 is selected.   Packet captures should hopefully show some more details of why the client is failing. ... View more

The user may have some wlan policies in this location.   C:\Windows\wlansvc\Policies   If they are managed by admin a gpupdate should re issue these. You could delete these and then retry connecting.  Compare them to a working laptop.   Is a local cert installed on the laptop?  What does the nps policy on radius use to allow the user to connect? gpo membership?    Event viewer may provide some guidance if driver related.   ... View more