Safari 15 has NSURLSession Websocket enabled by default.  This causes media to fail to connect and the following message is displayed:

To join CafeX via Safari 15 please disable the NSURLSession Websocket feature.  To disable please complete the following on your relevant platform. 


Selecting from the menu bar Safari > Preferences > Advanced and check Show Develop menu in menu bar


Select Develop > Experimental Features > NSURLSession WebSocket to remove the checkbox

Restart Safari


Settings > Safari > Advanced > Experimental Features and move the toggle switch off for NSURLSession Websocket