This has NOT been resolved. I've tried all the settings and check to verify I have the latest updates. I have to disable WIFI in order to get connection to the internet. WHERE'S THE FIX.....
I will tell you this is not a Samsung issue. I have Verizon and even with my old Motorola phone I could not force WiFi calling, it's the carrier. Where I live I might get one bar of 3G with Verizon depending on which way the wind blows, or maybe 1x data, but it jumps around so much it basically disables the ability to use WiFi calling since you cannot force it due to carrier restrictions. It is preferred only, but the network will ALWAYS prefer a cellular signal over WiFi for whatever reason. It is ridiculous yes, but not a Samsung or phone maker issue. I ended up getting an extender through Verizon for free because of it.
I should also probably point out that Verizon is retiring their CDMA service as of January 1st. It will continue to work only for existing customers until they replace their phones. That leaves Sprint as the only CDMA carrier left because the technology is inferior and has already been abandoned by everyone else who previously used it.
On AT&T, S10+, Android 10(& Android 9), WiFi affects MMS. Either it makes downloading MMS slow or stops. I have to turn off WiFi then manually download messages.
It's super annoying.