Erratic wifi speed on kde/plasma

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1

Hi,

I have wifi speed really special as you can see (testing on local network) :

Screenshot_20251231_145150
Screenshot_20251231_145150836×356 6.41 KB

It’s network speed (i have only wifi) with btop. 1 dot = 2s, top is > 10MB/s and low is around 2MB/s.

So the speed variate from x second at 2MB/s to x seconds at maximum speed. The timing is allways the same.

If i start the computer normally and log only in console, start network with nmtui, i got normal speed (beetween 8MB/s and 15MB/s). Then, if i stop connexion, log off then log on with graphical going to KDE, i get again that strange wifi speed timing.

Any idea why in console without KDE its working, but not with KDE. I already tried disabling power management with no success, but it make no sense that happen only with KDE.

It’s like a process is limiting the speed, but i don’t know how to find it. FW is disable.

Thanks,

My set up :

Operating System: Debian GNU/Linux 13
KDE Plasma Version: 6.5.4
KDE Frameworks Version: 6.20.0
Qt Version: 6.9.2
Kernel Version: 6.17.13+deb14-amd64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × Intel® Core™ Ultra 9 285H
Memory: 32 GiB of RAM (30,7 GiB usable)
Graphics Processor: Intel® Graphics
Manufacturer: ASUSTeK COMPUTER INC.
Product Name: ASUS Zenbook 14 UX3405CA_UX3405CA
System Version: 1.0

2

You can try to disable/remove the plasma network applet and see that changes something. (or even uninstall it, package plasma-nm).

That’s the only component that rely talks to the backend NetworkManager.

It might be for instance, that the applet triggers a wifi scan every few seconds, or other business occupying the Wifi ship hingering throughput (authentication, negocitation…).

You can manage your wifi through command-line using nm cli.

I think I am affected by this as well or at least I have been dazzled by the same rollercoaster of Wifi transmission.

Please share your findings. Any clues you might find would help to eventually fix this.

Plasma-nm is lightly maintained this days, but for such an issue I would be happy to help.

3

I can confirm myself that deactivating the plasma network manager applet did improve throughput stability.
Opening the applet causes a fall of throughput at least.

4

Hi,

Thanks for your answer, i tryed it but get no change.

In fact, i didn’t find how to disable it, so i remove it, reboot, then connect with nmtui and got same problem.

I don’t know if there is a way to trace what happen to packet or connection

5

That’s in the systray settings (right click on the arrow), mark it as disabled in the “entries” tab.

I have no clue then if plasma-nm has been removed, what might cause this.

6

Ok, i don’t have plasma-nm but network. I suppose it’s the same :slight_smile:

7

So, the problem come from kdeconnect after lot of cleaning of garbage stuff (why do i have useless gnome apps ?, it’s a clean install from april 2025 …), i finally buy a brain and look at /etc/xdg/autostart and kill process (i should started there) , starting by kdeconnect

and … it’s a win, i get now >10MB/s

(i don’t think i need it, looks like a DNLA/upnp media server interface)