SUMMARY Most recent KDE NEon updates (installed on Dec 5, 2019) disabled network. If I boot to the most recent kernel version for my machine (4.15.0-72-generic #81-Ubuntu), the network does not work at all. But if I instead use recovery boot for the same kernel version, my network activity is functional and normal. STEPS TO REPRODUCE 1. Boot to 4.15.0-72-generic #81-Ubuntu 2. 3. OBSERVED RESULT Network does not function at all, and all command line network tools I've used fail, even ping, which reports "ping: sndmsg: operation not permitted". EXPECTED RESULT Normal network activity, which is achieved by using the "recovery" boot of the same kernel version. SOFTWARE/OS VERSIONS Windows: Windows 7 Professional macOS: Linux/KDE Plasma: 4.15.0-72-generic #81-Ubuntu (available in About System) KDE Plasma Version: 5.17.4 KDE Frameworks Version: 5.64.0 Qt Version: 5.13.2 ADDITIONAL INFORMATION I was able to verify that it was indeed the recent KDE Neon configuration that was causing the issue, by also dual booting to Windows 7, opening Firefox to verify connectivity, then running speedtest.net to verify speed. All functions and settings were as expected including full duplex and 1000mbps, as they were in the linux recovery boot.
Scratch this bug. I tried experimenting with my VPN, and found that removing it, then reinstalling, solved the connection problem. I apologize for the false alert.