[SOLVED] Plasma as DE on top of Proxmox - Network Manager thinks Plasma is offline

S

Steve087

New Member
Sep 15, 2025
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Hi

I have 2 identical MiniPCs. I want to create a Proxmox HA-cluster but I also need one of the MiniPCs as MediaCenter with video output.
I first tried iGPU passthrough but unfortunaely this doesen't work due to the famous AMD reset-bug.

My second take at this, is to install the Desktop Environement on top of Proxmox. I have done that via tasksel. KDE Plasma is running. However Plasma or parts of it, e.g. the Network-Manager and Discover think the DE is offline. My understanding is that this is the case because Network Manager does not see the vmbr0.

I tried to edit /etc/NetworkManager/NetworkManager.conf and set managed=false to managed=true under [ifupdown]. This only makes my ethernet interfaces visible to network-manager but not the vmbr0.

How can I fix that and get Plasma to a state that it correctly reflects online/offline status?

Here some logs:
Code: 
root@gateway:~# cat /etc/network/interfaces
# network interface settings; autogenerated
# Please do NOT modify this file directly, unless you know what
# you're doing.
#
# If you want to manage parts of the network configuration manually,
# please utilize the 'source' or 'source-directory' directives to do
# so.
# PVE will preserve these directives, but will NOT read its network
# configuration from sourced files, so do not attempt to move any of
# the PVE managed interfaces into external files!

auto lo
iface lo inet loopback

iface enp195s0 inet manual

iface enp196s0 inet manual

iface wlp194s0 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.1.137/24
        gateway 192.168.1.1
        bridge-ports enp195s0
        bridge-stp off
        bridge-fd 0
        bridge-vlan-aware yes
        bridge-vids 2-4094

source /etc/network/interfaces.d/*
root@gateway:~#

Code: 
root@gateway:~# cat /etc/NetworkManager/NetworkManager.conf
[main]
plugins=ifupdown,keyfile

[ifupdown]
# managed=false
managed=true
root@gateway:~#

Also after installing Plasma my logs get flooded with these messages (dmesg):
Code: 
[ 2720.923048] audit: type=1400 audit(1758206290.422:484): apparmor="DENIED" operation="create" class="net" info="failed protocol match" error=-13 profile="/usr/sbin/cupsd" pid=12104 comm="cupsd" family="unix" sock_type="stream" protocol=0 requested="create" denied="create" addr=none
[ 2720.923312] audit: type=1400 audit(1758206290.422:485): apparmor="DENIED" operation="open" class="file" profile="/usr/sbin/cupsd" name="/etc/paperspecs" pid=12104 comm="cupsd" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
[ 2720.924271] audit: type=1400 audit(1758206290.423:486): apparmor="DENIED" operation="create" class="net" info="failed protocol match" error=-13 profile="/usr/sbin/cupsd" pid=12104 comm="cupsd" family="unix" sock_type="stream" protocol=0 requested="create" denied="create" addr=none
[ 2720.925752] audit: type=1400 audit(1758206290.425:487): apparmor="DENIED" operation="create" class="net" info="failed protocol match" error=-13 profile="/usr/sbin/cupsd" pid=12104 comm="cupsd" family="unix" sock_type="dgram" protocol=0 requested="create" denied="create" addr=none
[ 2720.929202] audit: type=1400 audit(1758206290.428:488): apparmor="DENIED" operation="create" class="net" info="failed protocol match" error=-13 profile="/usr/sbin/cupsd" pid=12105 comm="dbus" family="unix" sock_type="stream" protocol=0 requested="create" denied="create" addr=none
[ 2720.929216] audit: type=1400 audit(1758206290.428:489): apparmor="DENIED" operation="create" class="net" info="failed protocol match" error=-13 profile="/usr/sbin/cupsd" pid=12105 comm="dbus" family="unix" sock_type="stream" protocol=0 requested="create" denied="create" addr=none
[ 2720.929304] audit: type=1400 audit(1758206290.428:490): apparmor="DENIED" operation="create" class="net" info="failed protocol match" error=-13 profile="/usr/sbin/cupsd" pid=12105 comm="dbus" family="unix" sock_type="stream" protocol=0 requested="create" denied="create" addr=none

And these (journalctl):
Code: 
Sep 18 16:41:41 gateway systemd[11470]: drkonqi-coredump-launcher.socket: Unit needs to be started because active unit sockets.target upholds it, but not starting since we tried this too often recently. Will retry later.
Sep 18 16:41:44 gateway plasmashell[1762]: org.kde.plasma.nm.libs: Wireless scan on "wlp194s0" failed: "Scanning not allowed while unavailable"
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket - Socket to launch DrKonqi for a systemd-coredump crash was skipped because of an unmet condition check (ConditionUser=!@system).
Sep 18 16:41:52 gateway systemd[11470]: drkonqi-coredump-launcher.socket: Unit needs to be started because active unit sockets.target upholds it, but not starting since we tried this too often recently. Will retry later.
Sep 18 16:41:54 gateway plasmashell[1762]: org.kde.plasma.nm.libs: Wireless scan on "wlp194s0" failed: "Scanning not allowed while unavailable"

What is this and how can I correct whatever is wrong?


I shortly tried with GNOME and with GNOME I do not see the drkonqi-coredump logs. I don't linke GNOME though and would prefere to have Plasma everywhere.

Thank you very much for your help and time.
 
You don't want NetworkManager to manage vmbr0 and by default it won't because it ignores any interfaces that are managed by ifupdown. You had to override that behavior by changing the config file. Change it back to "managed = false" in the ifupdown section and it will stop complaining and vmbr0 will go back to working as well.

If you want to use NM to manage the wifi you can do that, otherwise you might as well just remove NM altogether. There's probably a way to get NM to manage vmbr0, but why?

Also, you get no DrKonqi errors under Gnome because that is specific to KDE Plasma. Gnome doesn't use it.
 
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BobhWasatch said:
You don't want NetworkManager to manage vmbr0 and by default it won't because it ignores any interfaces that are managed by ifupdown. You had to override that behavior by changing the config file. Change it back to "managed = false" in the ifupdown section and it will stop complaining and vmbr0 will go back to working as well.

If you want to use NM to manage the wifi you can do that, otherwise you might as well just remove NM altogether. There's probably a way to get NM to manage vmbr0, but why?

Also, you get no DrKonqi errors under Gnome because that is specific to KDE Plasma. Gnome doesn't use it.
Click to expand...
Thank you very much for your reply. I don't want to manage the interfaces with network-manager. I just need network-manager to reflect offline/online state correctly. Because if it doesn't then Discover and other Plasma programs simply refuse to connect to the internet even though this would be possible. Btw I had the same issue with GNOME also there, Software refused to connect to the Internet and GNOME reported that my host was offline when the Internet was reachable via Firefox and ping just fine. No clue why.
 
Last edited:
May I ask what you want to achieve with PVE and a GUI on the same machine? For Desktop virtualization virt-manager or virtualbox might fit better
 
Johannes S said:
May I ask what you want to achieve with PVE and a GUI on the same machine? For Desktop virtualization virt-manager or virtualbox might fit better
Click to expand...
From the opening post:

I have 2 identical MiniPCs. I want to create a Proxmox HA-cluster but I also need one of the MiniPCs as MediaCenter with video output.
I first tried iGPU passthrough but unfortunaely this doesen't work due to the famous AMD reset-bug.

My second take at this, is to install the Desktop Environement on top of Proxmox. I have done that via tasksel. KDE Plasma is running. However Plasma or parts of it, e.g. the Network-Manager and Discover think the DE is offline. My understanding is that this is the case because Network Manager does not see the vmbr0.
 
  • Like
Reactions: Johannes S
Steve087 said:
Thank you very much for your reply. I don't want to manage the interfaces with network-manager. I just need network-manager to reflect offline/online state correctly. Because if it doesn't then Discover and other Plasma programs simply refuse to connect to the internet even though this would be possible.
Click to expand...
This is not true. KDE Plasma doesn't care how the networks are managed, just that they are up when needed. I run a VM with KDE Plasma and no Network Manager at all and it works fine. Indeed, I do not get the status of the network in my systray by why is that important for a server? It isn't as if you are running around connecting to different wifi networks with a server that's part of a cluster.

The reason it appears not to work is because you changed the default settings in order to get that online/offline state display. Interfaces either need to be managed by Network Manager or by ifupdown but not both.
 
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You can in fact use Network Manager to manage any non-PVE interfaces you may have. Another Ethernet or Wifi or whatever. Just put the PVE interfaces in /etc/network/interfaces and leave the others unconfigured so Network Manager can handle them.
 
BobhWasatch said:
The reason it appears not to work is because you changed the default settings in order to get that online/offline state display. Interfaces either need to be managed by Network Manager or by ifupdown but not both.
Click to expand...
not true, I had this exact same issue with Gome and KDE Plasma after a default install and I installed this multiple times already.
 
BobhWasatch said:
just that they are up when needed.
Click to expand...
That here is the problem. Since all the adapters and bridges are managed by ifupdown network-manager doesn't see any and therefore reports as offline even though the system isn't. And I care because other DE services depend on that status and simply do not work if the status is reported as offline e.g. Discover.
 
Steve087 said:
That here is the problem. Since all the adapters and bridges are managed by ifupdown network-manager doesn't see any and therefore reports as offline even though the system isn't. And I care because other DE services depend on that status and simply do not work if the status is reported as offline e.g. Discover.
Click to expand...
You can always remove Network Manager. It is absolutely not required for KDE Plasma to work.
 
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got rid of the cups error logs by purging cups cups-filters and cups-browsed. I have no printer attached on this machine and do not need to print from this machine either.
Somehow the DrKonqi errors stopped, I can't see new ones anymore. No clue what changed or if this is related to the stuff I have uninstalled.
 
I was not fully correct about the drkonqi messages filling up my log. They where back. I did some more research. First I wanted to uninstall drkonqi but this would have removed most of KDE. Silencing it by stopping the service with sytemctl did also not work for me (not an expert, maybe I did something wrong).
The messages only appear if I have remote sessions either via SSH or via webgui with the root user. My workaround was to create an admin user to manage proxmox and ever since my logs are clear of drkonqi messages.
 
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