Should IPv6 work with undionly?

[myxal]

Hello. Should IPv6 work with undionly iPXE images (BIOS, UEFI)?

I thought I'd try out netboot.xyz in my dual-stack network by just putting its entry into existing menu, and unfortunately didn't get very far - iPXE keeps reporting "Connection timed out" on the very first IPv6 download - https://boot.netboot.xyz

Digging deeper with tcpdump and Wireshark, it seems undionly iPXE doesn't respond to Neighbor Solicitation at all. If, by sheer luck, the client's LLA was in the router's table from when it was used by a full OS, but GUA wasn't, I'd see how the HTTPS request went out, the response came back on the WAN interface, but nothing was forwarded into LAN. The neighbor table entries for the client during this ordeal were in the router (Linux machine) marked as INCOMPLETE or FAILED.

The iPXE image is an undionly.kpxe or .efi provided by Ubuntu 19.10, underlying firmware is a Marvell Yukon PXE (BIOS) and Intel PXE w/vmWare (UEFI)

I ended up trying netboot.xyz's ipxe image (on ISO) on vmware (UEFI), which includes more NIC drivers, and that works fine.