I dont know. Looking at the source they seem to have included possibly 3 different methods of communicating. Its my understanding if they use normal udp alot of windows clients wont work.
I did a bit more reading and it seems as though iptables is essentially getting a ‘clone’ packet, thats why the rules are triggering.
Its extra odd that enabling the firewall rules trigged a “send_packet: Operation not permitted” error from dhcpd, though for only some of the packets it send, and yet the client did receive a fresh new ip anyways.
Good information on the subject is not easy to find.