The worst thing: Occasionally it *does* connect, things work for a while, then crawl to a halt, then work again. I have no idea how to reproduce or even describe the issue to support except as “doesn’t work, most of the time”

The holy wrath of my family members will very soon descend upon me, once they discover what me updating all of the APs and switch means for their connectivity. Wish me luck.

Not that it helped me so far, but option-click on the Wi-Fi symbol shows an “enable wi-fi logging” menu item that fills a /var/log/wifi.log file with quite a lot of unhelpful messages. But they seem to indicate I may actually suffer from some password/auth/roaming problem