a quick update: in the few weeks i’ve been using this fix, i have since seen the notification come back up again from time to time, but it seems the fix does still hold. you can just disregard the notification (or silence it if you’d rather do that), tasker will still handle making the switch for you.
as of the one UI 3.0 / android 11 update, there is now a solution for this that seems to work 100% of the time via tasker without any further interaction from the user. one profile and one task and it will keep you on wifi preferred...i've had this running for over a week now and it has worked perfectly. https://www.grecobon.com/2021/01/unlocked-galaxy-s20-wifi-calling-issues/ tldr - since the android 11 update, there's now a custom system setting that controls this that we can monitor and change via tasker. the custom setting you're looking for is wifi_calling_preferred1. create a tasker profile that will automatically set it back to wifi preferred as soon as it changes to cellular preferred. my tasker profile and action are at the link above, as well as on taskernet (link in the blog post).
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