In my setup, i've got dhcp for IPv4 and IPv6 without dhcp. Same result. I could reproduce the bug in a vm and on a notebook There is a process in zombie state: [netcfg]. Its parent process seems to be udpkg --configure --force-configure netcfg A workaround is to kill the process dhcp6c -c /var/lib/netcfg/dhcp6c.conf -f eth0