I just updated my Iphone to IOS 14. Apple has added a feature which can, and did with my IPhone, cause a major issue. It’s called WiFi Tracking and allows the new version to provide a random MAC address when joining or reconnecting with a network.
The first I realized that it was a problem (with my Eero Mesh) was when every Wyze device showed up as offline. Apparently it works with some WiFi and not others. Second clue was other apps began reporting Certificate issues.
This feature is buried in Settings/WiFi/(Click the Info Icon by the actual network), so it is specific to each network. Turning this off solved my problem (after much searching!)
It appears to occur with some WiFi systems and not others.