Oddly, I noticed that since end of last week my ethernet connection via usb c is unstable (connecting/disconnecting) at work.
Using wireless is no problem. I never had this problem on EOS before, must be the new plasma perhaps. Don’t even know how to begin troubleshooting this issue.
Before I ask for troubleshoot help, wondering does anyone have a similar issue on KDE plasma 5.21, most recent kernel and all up to date EOS system?
Are you able to connect it via just usb to see if it’s different?
Do you mean usb2-ethernet adapter?
Edits: problem occurring using usbc with ethernet adapter. Could be worth a try with usb2 to ethernet tomorrow at work…
I guess that’s what I mean? You have it connected now via USBc to?
Edit: Is it currently a usbc to Ethernet adapter?
Have you tried a different DE?
No not yet, I think I will try to bring my other computer with xfce and try tomorrow. So at least I can exclude a problem with the network or cable.
then come back to work my way through possible problem on my kde laptop.
Thats a great suggestion. Perhaps next on the list would be to try another DE to check whether anything is wrong with the usb c connection on the laptop or recent update with kde.
I don’t think it is related to Plasma update, but I could be wrong easily, and this seems like the easiest way to rule it out.
Ok, tried on both eos with xfce and kde but this time using another ethernet adapter via usb2. It works normal 
Seems that there is a problem with the usb c adapter or ethernet connection via usb c. Will have to investigate whether it is hardware or driver related.
That’s why I wanted you to try the usb to ethernet as i read somewhere there is an issue with usb c to ethernet adapter. I can’t seem to find where I read it? I just wanted to see if it worked on a normal usb to ethernet as I have an HP that also only has wifi only and I would have to use an adapter so I was already thinking of getting a usb to ethernet. Glad it works.
Oddly it worked well via usb-c, so one of the updates, I suspect from the past two weeks did something or the adapter somehow broke. There were a lot of upgrades including kernel and plasma.
Difficult to test, would have to purchase another one of these or perhaps there are cli tools to test such hardware adapters. If you find the info you read please post here.
For now I guess it will be usb(no c)- ethernet adapter. Thanks for the idea though, it is KISS and works.
Did you have to go out and buy one?
I was lucky and found an old usb/ethernet adapter.
Could it be related to the AMD mainboard usb issue?
Some info here:
AMD is investigating a problem with some AMD mainboards and USB instability issues.
I actually have an intel core i9, Lenovo thinkpad P1.
Edit: since I can dual boot into windows I can further check if it is hardware or linux driver related.