This is an odd networkmanager bug, I have not fully understood it, but there are edge cases involving "secondary connections" causing it. My setup worked very fine for a long time, until I started adding multiple wireguard connections and DISABLING autostart for them (as I have a preferred one). Suddenly, wifi still worked but pluggin in ethernet would blink back and forth ethernet/wifi and then ethernet would disconnect. Journalctl shows the following: Feb 05 23:12:19 PC kernel: r8169 0000:2f:00.0 eth0: Link is Up - 100Mbps/Full - flow control off Feb 05 23:12:19 PC systemd[1]: Starting Network Manager Script Dispatcher Service... Feb 05 23:12:19 PC systemd[1]: Started Network Manager Script Dispatcher Service. Feb 05 23:12:19 PC NetworkManager[1159]: <warn> [1770329539.6766] policy: secondary connection '<AUTOSTARTING VPN> (020843d9-c911-4b2f-9562-8a887b7ff9ec)' auto-activation failed: The connection is not a VPN. Feb 05 23:12:19 PC NetworkManager[1159]: <warn> [1770329539.6773] device (eth0): Activation: failed for connection 'Kabelgebundene Verbindung 1' Feb 05 23:12:20 PC NetworkManager[1159]: <warn> [1770329540.1355] policy: secondary connection '<AUTOSTARTING VPN> (020843d9-c911-4b2f-9562-8a887b7ff9ec)' auto-activation failed: The connection is not a VPN. Feb 05 23:12:20 PC NetworkManager[1159]: <warn> [1770329540.1361] device (eth0): Activation: failed for connection 'Kabelgebundene Verbindung 1' Feb 05 23:12:20 PC kded6[3064]: Failed to notify "Created too many similar notifications in quick succession" Feb 05 23:12:20 PC NetworkManager[1159]: <warn> [1770329540.5657] policy: secondary connection '<AUTOSTARTING VPN> (020843d9-c911-4b2f-9562-8a887b7ff9ec)' auto-activation failed: The connection is not a VPN. Feb 05 23:12:20 PC NetworkManager[1159]: <warn> [1770329540.5662] device (eth0): Activation: failed for connection 'Kabelgebundene Verbindung 1' Feb 05 23:12:20 PC kded6[3064]: Failed to notify "Created too many similar notifications in quick succession" Feb 05 23:12:21 PC NetworkManager[1159]: <warn> [1770329541.0175] policy: secondary connection '<AUTOSTARTING VPN> (020843d9-c911-4b2f-9562-8a887b7ff9ec)' auto-activation failed: The connection is not a VPN. Feb 05 23:12:21 PC NetworkManager[1159]: <warn> [1770329541.0181] device (eth0): Activation: failed for connection 'Kabelgebundene Verbindung 1' Feb 05 23:12:21 PC kdeconnectd[3280]: LanLinkProvider/newConnection: Host timed out without sending any identity. QHostAddress("::ffff:192.168.1.242") Feb 05 23:12:21 PC kdeconnectd[3280]: LanLinkProvider/newConnection: Host timed out without sending any identity. QHostAddress("::ffff:192.168.1.242") Feb 05 23:12:28 PC kernel: r8169 0000:2f:00.0 eth0: Link is Down Feb 05 23:12:30 PC plasmashell[3103]: qrc:/qt/qml/org/kde/plasma/private/clipboard/UrlItemDelegate.qml:49:17: TypeError: Cannot read property 'height' of null Feb 05 23:12:31 PC systemd[1]: NetworkManager-dispatcher.service: Deactivated successfully. This is similar, if not nearly identical to this bug: https://forum.manjaro.org/t/116617 That bug linked to this upstream issue, somehow it was marked as resolved: https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/205 What causes the issue - Have a Wifi connection automatically connect to a Wireguard VPN (this seems to be automatically set if a VPN is set to autostart) - Also have an ethernet connection autoconnect to a VPN - now both connections may seem to fight over that secondary connection, maybe a race condition? What solves it for me: disabling "auto connect to VPN on this connection" for the ethernet connection. the VPN itself is still configured to autostart, the one affected Wifi also still auto-connects to the VPN. I am not sure how this affects the VPN reliability. While it is an upstream bug, some component (may it be NetworkManager or Plasma) sets these conflicting configs, causing this potential race condition and the ethernet connection failing to connect. Operating System: NixOS 26.05 KDE Plasma Version: 6.5.5 KDE Frameworks Version: 6.22.0 Qt Version: 6.10.1 Kernel Version: 6.18.8 (64-bit) NetworkManager 1.54.3 (nixpkgs) wireguard-tools 1.0.20250521 (nixpkgs) Potential duplicate: https://bugs.kde.org/show_bug.cgi?id=507770 Similar looking issues: - https://bugs.kde.org/show_bug.cgi?id=425625 - https://bugs.kde.org/show_bug.cgi?id=435603
I've had similar, pretty annoying, problems with WireGuard. Reading the upstream bug report, it sounds like it's ultimately things on their end being a bit weird, not too much we can do here in plasma... As I see it, the bug report upstream was closed because the person found a workaround; I think it's worth opening another issue in networkmanager