5 seconds lag when running Kubuntu with built in window server

[guidosch]

Hi,

When I use the build in window server from nxagent I can connect but every keyboard stroke and mouse move has a lag of round 5 seconds. When I disable the Kubuntu window server via (systemctrl stop sddm) and use the one which comes with nxagent everything works fine and without any lag. Any idea what I have to to to use the window server provided with Kubuntu?

Thanks for any hints…

[Britgirl]

By window server I think you mean display server 🙂

It’s not clear what’s slow exactly. Is typing only slow with NoMachine’s only display server? What version of Kubuntu are you using?

[andro]

I use NoMachine 6.12.3.  I  connect from Windows to Ubuntu. I also have the problem with the 5s delay.

I discovered that this problem only occurs when the Ubuntu machine doesn’t have its own physical display. So, I plug in the HDMI on Ubuntu machine, problem disappears and the remote connection is now responsive.
I unplug the HDMI from the Ubuntu machine, and the remote connection has 5s delay.

[andro]

I have a similar setup connecting from the same Windows machine to another Manjaro machine. There I don’t have this problem yet…

[Britgirl]

@andro, Manjaro is Arch-based if I am not mistaken. Although running NoMachine on Arch isn’t officially supported, we are investigating multiple issues regarding this particular distro (you can search the forums if you like). We’ll update the appropriate topics with our findings.

Regarding Kubuntu, it’s headless, so this may be of interest to you.

How to solve black screen on headless machines
https://www.nomachine.com/AR03P00973

[guidosch]

My problem with the lag is gone (lag was when typing with the keyboard or dragging a window). I installed the enterprise version and still had the same lag. But after a few restarts I now get the good performance either with kubuntu or the built in display server fron NoMachine. I did not change any settings but it works now. Thanks for your help!

[andro]

Ok, I am saying that on Manjaro everything works fine. It is Ubuntu where I have this problem.

[andro]

Additional info, if it will prove useful…

I connected to the problematic Ubuntu computer via NoMachine. I physically connected a keyboard to that Ubuntu computer.
I opened a text editor and started typing with the keyboard that is physically connected to the Ubuntu computer. Still, I experience 5s delay.

I’m sure you were already aware of this, but this made me realise that the delay is only happening on the video feed from the remote computer to the on I’m connecting from. There is no significant delay in sending the mouse and keyboard controls towards the remote computer.

[andro]

Guidosch, does your remote computer also has its own physical display? Or is it “headless”?

[guidosch]

My remote computer also has a physical display attached.

[andro]

Guidosch, can you try and see whether the problem with delay comes back when you unplug the physical display?

[fra81]

From what you both say, this looks like a problem with the video drivers rathen than with NoMachine. In one case I see this was fixed by plugging a HDMI, in the other case by rebooting and it is confirmed further by the fact that there is no delay when using the display server provided by NoMachine. In fact some drivers/cards can be fast at rendering but much slower when images have to be pulled back from the GPU. I would try to check for newer versions of proprietary or OSS drivers.

[Author]

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