Thanks, vasa1. So Kubuntu nor Firefox should be the issue. No other device. I restarted my router a few days ago, that didn't make any difference. I can reset my router, later. It will mean that I will need to redo all my settings. No recently changed settings. If no one else has any other ideas to try, I will reset my router, later, when I have the time to redo my settings and evaluate the outcome. Thanks very much for now!