1

I have a custom made (not by me) imaging device here. It connects to a computer via ethernet cable. The companying application software guides the user in the process of acquiring an image.

So far so good.

I'm now trying to use that device on another computer, which does not have an internal network interface. So I use an external QNAP (QNA-UC5G1T) network interface.

This device uses jumbo packets so I already configured the network interface to use jumbo packet 9k.

However the image acquisition fails on this laptop.

While investigating the issue with Wireshark I noticed:

[bad udp length 8024 > ip payload length] len=8016

I learned how to use Wireshark today so I might be guessing wrong but that sounds like the device is messing with something. Isn't?

And why it works fine in the other laptop?

enter image description here

Can I make it work on the new laptop by changing the network interface properties?

enter image description here

Following are the options of qnap external network interface:

enter image description here

enter image description here

enter image description here

Improve this question
4
  • If you expand the UDP header in the bottom window it should show the Length field. This evidently doesn't match the hardware-detected packet length. Different cards and drivers may respond differently to this error.
    – stark
    Mar 18, 2022 at 14:46
  • That device is spewing a lot of bad stuff. It just seems insanely buggy. Update its OS and NIC drivers.
    – Spiff
    Mar 18, 2022 at 15:56
  • @stark I added another image with fields expanded, do you see anything there? Any suggestion on what should I try?
    – KcFnMi
    Mar 19, 2022 at 10:29
  • @Spiff when I use the device on a laptop with internal network interface it works fine. Wireshark do not show the bad length issue. I tried a few different laptops. I have two of this qnap external network adapter, both present the problem. I'm actually not sure what to conclude of this. Any chance the problem might be on the qnap network adapter?
    – KcFnMi
    Mar 19, 2022 at 10:46

1 Answer 1

Reset to default
0

Let me answer my own question.

That qnap network interface is usb-c and it was connected to macbook 16"(tried both windows on bootcamp and on parallels vm).

The qnap originally came with a usb-c/usb short cable. But since macbook do not have usb I was using the original power cord (which is a long usb-c/usb-c cable) to connect the qnap.

After all kinds of tests I tried to connect the qnap via an external display's usb port, using the usb-c/usb short cable. And, looks like everything works this way.

Conclusion, long usb-c/usb-c cables won't work.

Also tried another usb-c/usb adapter, cheap of unknown brand or model. This also didn't worked.

Perhaps there's some technical specs of usb-c/usb cables I'm not aware of. Appreciate if someone can add more info.

Improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .