HostInit: host PXE gets DHCP lease but PXE-E21 immediately — is enabling HTTP Boot via Redfish the right fix?

[jingjingl1]

Context

I am onboarding a machine (BlueField-3, NVIDIA H8230 host, AMI MegaRAC 13.05 BMC) through NICo. After carbide-api moves the machine to HostInit / WaitingForDiscovery, the host needs to PXE-boot to fetch the OS image.

What I observed

Host boots, NIC 58:A2:E1:D7:10:BE (BlueField host PF) runs DHCP and gets lease 20.1.1.5 from carbide-dhcp, Start PXE over IPv4... Station IP address is 20.1.1.5 PXE-E21: Remote boot cancelled. tcpdump on the L20 control-plane node captured 0 packets from that MAC, so no TFTP/HTTP request ever reached carbide-pxe.

Questions

1. Is enabling HTTP Boot via Redfish actually required for this step?
   The DHCP lease succeeds, so the network path from host → DPU → carbide-dhcp is working. Is PXE-E21 here caused by carbide-pxe not serving a TFTP NBP (i.e. it only speaks HTTP boot), or is there another reason?
2. Is the real root cause somewhere else entirely?
   Given that tcpdump on the control-plane node saw 0 packets, the failure may be before any protocol decision — e.g. the DHCP OFFER's next-server / bootfile fields are empty or wrong, causing the host firmware to cancel before even attempting a file transfer.