error finishing read!

What type of Ethernet chip is used on the motherboard?

dmesg | grep -i eth
(or sudo dmesg | grep -i eth)

should show this
 

Attached is a screenshot of the output.
Realtek is the onboard NIC.
The Intel NIC works well and has a MAX ping of 0.36 after one hour. 
This command 
 hardware-irq-coalesce-rx-usecs 0
I have not yet tested this command for the new Intel NIC.

Apparently others have already had a problem with the driver!?
groups.google.com/g/linux.debian.kernel/c/HJQTXTdpBJo?pli=1

Addendum
I have just looked again at my laptop, i.e. the first device on which I installed LinuxCNC, to see which NIC driver is installed there. The r8169 RTL8168 is also listed there. I also had the problem with the laptop with the long ping time.  I have also attached a screenshot of the laptop.

I have installed the driver mentioned here
( groups.google.com/g/linux.debian.kernel/c/HJQTXTdpBJo?pli=1 )
on my laptop (see attachment) and was able to reduce the max ping time from 14ms to 0.155ms for long-term ping.
This one line
# sudo apt-get install r8168-dkms
 would have saved me a lot of installation and configuration work.
Now LinuxCNC runs stable on my laptop.

Anton wrote:

I have installed the driver mentioned here
( groups.google.com/g/linux.debian.kernel/c/HJQTXTdpBJo?pli=1 )
on my laptop (see attachment) and was able to reduce the max ping time from 14ms to 0.155ms for long-term ping.
This one line
# sudo apt-get install r8168-dkms
 would have saved me a lot of installation and configuration work.
Now LinuxCNC runs stable on my laptop.

I forgot how hard i tried to get Debian to acknowledge some flaws in their distro. I also raised issues with the PREEMPT_RT development team. In the end noone cares.

I think in the end the fault lies with the Linux kernel as the R8168 is poorly supported by the R8169 kernel driver and the R8168 driver is not in the kernel. This is where DKMS comes in as it allows installation of kernel modules which are recompiled if you use another kernel (most of the time)

Sorry I did not read your post earlier. This is all covered in my Debian config document. I need to add a bit on IRQ pinning which is in a sticky on the forum here
docs.google.com/document/d/1jeV_4VKzVmOI...diY/edit?usp=sharing

Hello rodw,
the document
docs.google.com/document/d/1jeV_4VKzVmOI...m1x7oiw8VcLFdiY/edit
is really great and would have helped me a lot as a beginner.
In your document there is a section "QtPyVCP, Probe Basic and EtherCAT" in which you recommend QtDragon. Do you know whether a version for lathes is also being planned?
I would like to familiarise myself with a GUI in the near future. I don't find Axis and Gmoccapy particularly appealing. My choice would now be Probe Basic Lathe, unless there is a QtDragon Lathe version.
Greetings from Marburg

I don't know about lathes. Is it mentioned in the docs? I thought one might be under way.