In installing a new Cisco RV320 router at the office, I ran into some trouble
with the DHCP server. My desktop could get an IP address, but my laptop
couldn't. The request (with sudo dhcpcd -d -4 eth0) would just timeout
without a response.
I compared the /etc/dhcpcd.conf file between machines and found that newer
Archlinux installs configure the duid option. Disabled that and viola,
dhcp works!