10.1.0

At service shutdown, such as during a system reboot, I wish to release the IP lease so that the dhcp server sees the system going down gracefully.

At boot:

dhcpcd.service - starts in managed mode
[email protected] starts for eth0

system acquires both DHPCv6 and DHCP v4 address.

At system shutdown:

[email protected] ExecStop runs --release %I
dhcpcd.service ExecStop runs --exit

Expect:

• dhcpcd sends DHCPv4 and v6 release before closing down interface

Actual

• DHCPv4 release is sent and seen by DHCP server (verified via packet capture).
• DHCPv6 release is received by DHCP server as garbled/corrupted
  -- Message type is 58 instead of 8, XID is wrong, etc.
  -- Possible that packet is being corrupted mid creation

Adding ExecStop=sleep 1 seems to resolve the issue for now, not ideal, but workable.

Will re-test with 10.2.4