New user -- nobody can hear me

I have tried jitsi, and set up a test meet. My other participant did fine, but they could not hear me. I was on an I-phone 8 running 13.3.1. I have a group meeting tomorrow, and need to debug, but don’t have any idea how.

I browsed through some developer threads, and found advice that if the features are not delivering, to reset the audio or video, whichever is giving trouble. Multiple times. Or to drop off and reconnect to the meeting, again several times. I had my users do this, and eventually all of them got good enough connections.