Watsapp call not working after iOS14 update

After update to iOS 14, WhatsApp Calling feature does not work, normal messaging works but the Video / Audio Calling is not working. It keeps asking me to switch from 4G to WIFI but none of them work. Everything was working fine before the update. I have re-installed WhatsApp, re-installed iTunes but still nothing works and even reset network setting and switched route on and off but with no help.

is there any solution to fix this .

Thanks