Help Force Wi-Fi calling preferred

[km2002]

My S8 (on Android 9) has of late developed an undesirable habit: It changes the preference on Wi-Fi calling depending upon its attachment to or detachment from a Wi-Fi signal. It's a preference: If it doesn't find Wi-Fi, it should fail over to cellular; but it should not reset my preference in the process. How can I force the setting to remain on Wi-Fi preferred whether I'm on a Wi-Fi connection or not?