In /usr/share/initramfs-tools/scripts/functions, function
configure_networking:

        for ROUNDTTT in 2 3 4 6 9 16 25 36 64 100; do
[...]
                dhcp|bootp|rarp|both)
                        ipconfig -t ${ROUNDTTT} -c "${IP}" -d "${DEVICE}"
                        ;;
[...]
        done

which means that if after all these retries, the DHCP server is still
not available (it may take dozens of minutes after a power outage),
remote unlocking the machine is impossible.

The retries should be configurable. In particular, it should at least
be possible to wait for an indefinite amount of time (without a large
delay between the retries).

https://salsa.debian.org/kernel-team/initramfs-tools/-/merge_requests/203

It adds IPCONFIG_TIMEOUTS to configure the timeout sequence and
IPCONFIG_RETRY=y to keep retrying until dynamic configuration succeeds.
The defaults stay unchanged.

The package builds with sbuild. In QEMU, the client obtained an address
when DHCP became available after 20 seconds. I haven't tested the full
remote-unlock flow.

                                            - Troy