Note: prior to upgrade to 25.12 - UNCHECK WAN6->Do not send a Release when restarting (i.e. send release). This helps shorten the time to get a new lease when 25.12 odhcp6c sends a renew/request using a new DUID.
The DHCP changes have largely gone smoothly (several reports vs thousands of users on snapshots, RCs and release).
The nature of the change has been to implement a DUID which is stable across (Ethernet) ports, upgrades and hardware changes. RFC8415 and its ancestors lay out clearly that the DUID is an opaque string which shall not be interpreted or have meaning, only compared. There are ISP that possibly expect to find a MAC in the DUID. Some ISP just need to let old leases expire before granting new ones. Some reports resolved themselves when the old leases expired.
Part of the change is to converge DHCP and DHCPv6 both to use the same DUID. In 24.10 it was -C<MAC> for DHCP and one of the device MACs for DHCPv6.
We added a Default DUID field in the UI under Global network options to show the DUID, or, if you know what you’re doing, to change it. IIUC, if you completely delete the value - DHCPv6 (odhcp6c) will use a device MAC (but your WAN IP will change again). Don't quote me on that.
| DUID Type | Example | Description |
|---|---|---|
| DUID-LLT | 0001000100000001<12-char-MAC> |
unix time (1 second) + MAC which some weird ISP want. |
| DUID-LL | 00030001<12-char-MAC> |
Link Layer MAC address. |
| DUID-UUID | 000476d043b90a0a4715bd8598ed4bdb8b3e |
is the new DUID type. |
The DUID is sent in the "Client ID" field. DHCP option 61 and DHCPv6 option 1.
See also this thread.