By default your DHCP will often not work because it is not listening on any interfaces.
All you have to do is edit this file:
vi /etc/default/isc-dhcp-server
then find the "INTERFACES" line and add each interface that should listen:
INTERFACES="br0 enp0s10"
interface, dhcpd, server, listens, debian, linux, mint, ubuntuby, default, dhcp, interfaces, edit, vi, etc, isc, quot, br, enp,