error finishing read!

yes of course

the screenshot you sent, it shows "no_isolcpus". I would try „isolcpus=5.7“ in grub command line. 

Hi unfortunately grub command line doesn't tell me anything. how do i get there and what command do i have to enter there?

edit the grub command boot file

sudo nano /etc/default/grub

Find the line: GRUB_CMDLINE_LINUX_DEFAULT=""
edit to : GRUB_CMDLINE_LINUX_DEFAULT="isolcpus=5,7"

Then save and exit: ctrl+x then press "y" to confirm

sudo update-grub

sudo reboot

Thank you for the information.
I thought it would be more complicated.
If I have understood correctly, then cores 5 to 7 are isolated. But what are these cores used for?
Don't you still have to assign the IRQ from the network card to a core?
I'll try later to see if Chris's instructions lead to an improvement. 

Unfortunately, the behaviour has deteriorated again. After starting LinuxCNC, the finishing read error now appears immediately. The motors can no longer be moved at all. Perhaps this laptop is simply not suitable.
Attached is the histogram and the ping with isolcpus=5.7.