My laptop was Win 11, using ethernet adapter to usb, now changed to Kubuntu 23 and adapter is obsolete; but i cannot find an ethernet adapter to usb port that will work with Kubuntu. Does anyone know a brand name for one? It must come with Kubuntu drivers. This is probably a common problem.
The lsusb program (with that adapter installed) might give us a hint as to what your problem is.
No. It is not a common problem. USB to internet adapters normally just work in Linux, without problems.