On my Raspberry Pi running Bullseye after running “sudo apt-get dist-upgrade” dhclient failed to start at boot. A local login and one could run “”sudo dhclient” and all would be well.
Fortunately the good folks at stackexchange had seen and solved the problem. Edit /etc/systemd/system/dhcpcd.service.d/wait.conf to change “/usr/lib/dhcpcd5/dhcpcd” to “/usr/sbin/dhcpcd”.