Thanks very much, Dave. In System Settings\ Network\ Connections\ Edit your Network Connections\ Wired, I see that Allow auto-negotiation is not enabled, Speed is set at 100 Mbit/s, and Duplex is set at Half. Well, that is weird. What is the reason for those settings? The Networks item in System Tray says: Connection speed: 1Gitb/s. I tried Network Connections setting Allow auto-negotiation enabled, and I tried speed setting 1000 Mbit/s and full-duplex, but that didn't make any difference. Which is no wonder, as my internet speed is not limited by Kubuntu settings, but by my VDSL, as shown in my router, since a couple of weeks or more. Anyhow, the Network Connections settings in System Settings and the discrepancy with the readings in System Tray are weird.