It used to work properly till android 10, however from android 11 (one UI 4) it only works on the mobile network.
Also both users should be on same mobile network. If anyone of us switch on wifi then the SMS service is initiated which shouldn't be the case. RCS should work on wifi network as well in Samsung Messages app.
A small note that both the phones are of Samsung & Advanced Calling and Messaging features are enabled for both of them
Just because of this we are unable to use the advanced features like sharing images, videos, audio, location ,etc.
Kindly requesting you to look on this on priority.
