FaceTime connection fail on iMac

I get connection failure on incoming and outgoing FaceTime video calls on my iMac. Works Ok on my iphone.

Running Sonoma 14.6.1.

On outgoing calls, recipient can see me but the call doesn't connect my end.

On incoming calls, FaceTime window pops up and I get my camera view - not the senders - and then get call failed pop up message.

Ideas anyone?

TIA

Peter