Environment: Firefox 85.0.1 (64 bit); Windows 10 (64 bit) I have established a websocket connection to my server. Everything is working fine in updating the several browser windows. With Firefox I got a problem. After I call my page with Firefox, actualization via the websocket connection are displayed fine in Firefox and other browser windows. My problem: If I call my page in Firefox and send data via <form> (simple generate a PDF without page refresh) my window didn't show the updates received via the websocket connection. It looks like, the connection to the server is lost or the incoming data is blocked/lost.

This is a problem just on Firefox. All other browser I tried (Chrome, Edge, Vivaldi, Opera, Cliqz, Brave) are working fine.