How do I fix 'Connection is unstable' during FaceTime calls on new iPad?

During FaceTime calls on my new iPad my session is interrupted with “connection is unstable”, the video part is interrupted, audio continues briefly, and then I’m cut off. iPad OS 18.2.1. This happens with incoming or outgoing calls but does not happen on my nor my wife’s iPhone. Our WiFi signal is strong. We’ve reset everything.

I have spent hours with Apple support who finally sent a new iPad but it happens with it also! My old iPad never had this problem. Help please.

[Re-Titled by Moderator]