Currently we have DHCP issues, some clients got DA some time, not all
the time.

Run etheral when client renew IP address, found following.

If the client does not get DA, only four DHCP packets: Discover, Offer,
Request, and ACK.

If the client does have a DA, two more packets: Inform, ACK. In these
very two packets, the DA was handout.

How could I correct this?