Works when plugged in at boot time, not when plugged in later (Linux)

Hi! I have an odd issue that has been consistent since I started using the 2.5Gb adapter about 4 months ago:

If I boot the computer with the adapter (USB) plugged in to my laptop (and a CAT7 cable connected to the adapter) I have a zippy, solid connection (1000Mb/s). Love it!

If I later unplug the USB adapter (with CAT7 connected) and plug it back in, everything seems to detect that the device exists, but it reports consistently that the link is not detected (cable unplugged). For example, sudo ethtool enx8cae4cdd3882 reports “Link detected: no”. Same with the graphical settings program for the network in my OS.

Similarly, if I do NOT plug in the USB adapter (with CAT7 connected) at boot time, and then later decide I would like to connect it, the USB device is added, but it’s still “Link detected: no”.

One additional (somewhat strange) piece of info: If I plug the USB adapter in at boot time, but leave the CAT7 cable disconnected, then boot up, and finally connect the CAT7 cable, the speed of the network connection drops significantly: sudo ethtool enx8cae4cdd3882 detects “Speed: 100Mb/s” instead of “Speed: 1000Mb/s”. Repeating this is consistent, and I never get 1000Mb/s unless I reboot.

Any thoughts or directions to explore? It’s really puzzling me. Thanks!

OS: Pop!_OS 22.04
Linux Kernel: 6.0.6-76060006-generic

Hello Duane,

Thanks for reaching out to us and welcome to our forums!

We have a troubleshooting software tool that can give me some more precise details on how the ethernet adapter is being detected with your Linux system. Please plug the ethernet adaptor into your computer, then go to this page and follow the instructions there:

I would recommend to contact us directly to our support email, we can take a deeper look at log files and provide further guidance.

Please visit our contact page and you can reference ticket 393722 in your email.

I look forward to hearing from you soon!


Product Owner
Plugable Support

Thanks, I used the plugdebug tool and attached two zip files as part of the support contact form. Looking forward to learning more!

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