SUMMARY while kcmshell5 kcm_networkmanagement works well with a "normal" pppoE-connection and ethernet-connections and so forth, it seems to support VLAN rather poorly. The nm-connection-editor from the Gnome NetworkManager suite works much better for VLAN, but cannot switch between ONLINE and OFFLINE. So currently while using this VLAN 7 profile, I do not utilize kcmshell5 kcm_networkmanagement at all because it just messes up everything in unpredictable ways and its display is not useful and is inconsistent. Since ISP Dt. Telekom has millions of customers, it is desirable for pppoE with VLAN frame-tagging to "7" to work as smoothly as a normal pppoE or as roaring-penguin-pppoE for that matter. STEPS TO REPRODUCE 1. follow https://gitlab.freedesktop.org/snippets/638 2. try to switch between ONLINE and OFFLINE 3. it won't work, so you must nmcli for that OBSERVED RESULT the kcmshell5 kcm_networkmanagement GUI is not much useable for controlling a VLAN profile, see also https://gitlab.freedesktop.org/NetworkManager/NetworkManager/issues/222 EXPECTED RESULT I expected a VLAN 7 pppoE connection to work as smoothly as a non-VLAN connection SOFTWARE/OS VERSIONS Linux/KDE Plasma: current Manjaro rolling release KDE Plasma Version: 5.16.3 KDE Frameworks Version: 5.60.0 Qt Version: 5.13.0 ADDITIONAL INFORMATION Kernel: 5.2.4-1-MANJARO
Unfortunately VLAN and other virtual connection types (Bond, Bridge, Team) are not really tested properly in plasma-nm, that's also why they are not enabled by default, but you have to enable them in configuration. I'm afraid that I don't have time to work on this right now or in near future, but I will happily review any patches you or someone else send me to fix this.
I kinda presumed this after reading prior speculations in a Ubuntu forum which linked to the commit initially disabled VLAN completely in 2017 or so, before it was re-enabled. Maybe I can take a look at the sources myself. Let's see.
To clarify, the package containing "kcmshell5 kcm_networkmanagement" is still installed and probably needs to be installed. But I don't click on it for editing the net profile to avoid trouble while using VLAN ID 7 frame-tagging. Instead, I use solely "nmcli" in a bash Konsole in order to set up the network and go online and offline.