I'm on the AT&T network and I have nothing but issues with wi-fi calling. I have 1 or no bars of service at home but I have very strong wi-fi. If I move from one spot while on a call it drops. I also have issues getting and sending text messages. As i said my wi-fi is very strong but nothing seems to work at home. Any ideas??? I thought wi-fi would alleviate any connectivity issues.
AT&T has a known issue with wifi calling. My wife's S9+ had poor battery life and inability to send and receive MMS. Disabling wifi calling on her phone eliminated the issues. I would recommend that you do the same.