Guest Can Open Room But No Sound/Video

Hi,

I am trying to get my friend in France to use my secure domain server but even though she allows use of her camera/mic se cannot see or hear anything.

She is running Win10 on a 6 year old laptop and her internet speeds are 8.7Mbts and 1.05Mbts.
I can see her window but nothing else. I tried again using the public server with the same results.
Using whatsapp I can see that both her mic and camera are activated but her window on my laptop shows both are not activated. My server does not limit guests and the public server was not set to mute mic or turn off the camera.

Can someone suggest why she cannot use Jitsi and what I could do to resolve the situation!?

Thanks