Remove any USB Ethernet entries that you might have put at the bottom of the /etc/dhcpcd.conf
I upgraded to buster stable and my RPi3B+ seemed like it was fire-walled. Above fixes ethernet ghosted connections, WIFI was working. I say ghosted because the Plymouth desktop showed a live connected eth0 and Ip address, for example, 192.168.1....
As per the answer by @smpita I also ran into this problem after doing the sequence of
sudo apt update
sudo apt upgrade
before installing Docker. Investigating the logs for dockerd using journalctl -xe I found errors indicating that the kernel was missing certain required features. Checking uname -a and ls /lib/modules/ I noticed that the versions of the ...