https://www.rfc-editor.org/rfc/rfc2131dhclient
- part of isc-dhcp-client
- runs on things that you put in /etc/network/interfaces
- config is /etc/dhcp/dhclient.conf
- ISP doesn't respond to discover
dhcpcd
- runs on pi for things not in /etc/network/interfaces
- can run in addition and populate stale values in adapter
- doesn't get required ipv6 as standard
- not needed because of settings in /etc/network/interfaces
- config is /etc/dhcpcd.conf
- needs to be disabled
# disable dhcpcd
sudo systemctl stop dhcpcd.service
sudo systemctl disable dhcpcd.service
# modify /etc/dhcp/dhclient.conf
end dhcp-client-identifier 1:dc:a6:32:c1:8f:ad
# adjust timeout
/etc/systemd/system/network-online.target.wants/networking.service
...
https://www.youtube.com/watch?v=yDXjsUUJnzo