Since Android 8.1, it's necessary for apps which want to determine the active WiFi name (SSID)
- to have the location permission,
- that location services are actually active (usually by enabling "location" in the Android quick settings).
This is because the WiFi name/SSID can theoretically be used to determine your location. For example, imagine that you're in the WiFi "Berlin Public Transport" – apps which can read this information could track your location just based on the WiFi name.
So, if you want to restrict DAVdroid synchronization to specific WiFi SSIDs on Android 8.1+, you need to
- give DAVdroid the location permission (DAVdroid will ask for it),
- have location services enabled on your device.
This is only required to restrict synchronization to specific WiFi networks. To restrict synchronization to WiFi networks in general, no additional permissions are needed.