SUMMARY After the recent updates, whenever my laptop wakes up from suspension, wired connection (via Ethernet adapter) is not restored and completely vanishes from the connections list in Network Manager (as if the wire has been physically disconnected). So far, I haven't found any way to restore it, which is insanely annoying. - Reconnecting the wire doesn't work; - Restarting "NetworkManager" and/or "networking" services doesn't help, but introduce more bugs (wireless connection stop working due to missing secrets); - Replacing "plasmashell" doesn't affect it; - Judging by "ifconfig" output, the Ethernet interface is UP and completely functional after suspension. STEPS TO REPRODUCE 1. Suspend to RAM. 2. Wake it up. OBSERVED RESULT Wired connection no longer works and is not visible in Network Manager. EXPECTED RESULT Wired connection to work normally. SOFTWARE/OS VERSIONS OS: KDE neon 5.16 Kernel: x86_64 Linux 5.0.0-25-generic Uptime: 14m Packages: 3086 Shell: bash 4.4.20 Resolution: 3280x1248 DE: KDE 5.61.0 / Plasma 5.16.4 WM: KWin GTK Theme: Breeze [GTK2/3] Icon Theme: breeze Font: Noto Sans Regular CPU: Intel Core i7-6700HQ @ 8x 3.5GHz [54.0°C] GPU: GeForce GTX 950M RAM: 1719MiB / 11898MiB ADDITIONAL INFORMATION Ethernet interface is "enp3s0f1". The device is "Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller".
So far, the only way to restore connection for me is a reboot. After reboot, Wired Connection becomes available as usual.
Found a workaround all of a sudden. Removing kernel module "r8169" (which is my Ethernet adapter driver) and then loading it again seems to restore the connection: # modprobe -r r8169 # modprobe r8169 Does it mean it's possibly a kernel-level bug?
Kernel bug confirmed: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1752772 Somehow, this is still present in 5.0.0 kernel. This has nothing to do with KDE's Network Manager.