fetchCurrentWithCompletionHandler works for me on iOS 14, but not on iOS 15 (the same code). Are there any additional limitations on accessing the WiFi information on iOS 15? (I did not ask for Hotspot Helper entitlement).

Interesting, for me WidgetCenter.shared.reloadAllTimelines() worked from Network Extension only during debugging sessions. When I tried to test it without debugger, it did not work. I tested with iOS 15.4.1 though. Could it be that the bug was fixed in a later iOS versions?