Hello Tina, I've had the same problem but have solved it. Even if you have Wifi calling enabled on your phone, it may just default to using the cellular signal from your nearest mast, even if that signal is quite weak. When you are at home, try switching on the AIRPLANE mode, and make sure your phone's wifi is switched on. This disconnects your phone from the cellular signal, and will force your phone to use Wifi calling. If this works, you will get a notification, or a symbol may appear at the top of your screen showing a telephone and a Wifi signal. Or when you go into your phone app to make a call, a wifi symbol will appear on the connect call button near the bottom of your screen. This fix works for me, and I've got a Samsung A52. You just have to remember to switch the airplane mode off again when you are out and about, so you can make and receive calls using the cellular signal as normal.
