PXE Server problem on UEFI Mode

Hello, I am currently using NixOS and have set up a PXE server using the Pixiecore module (https://github.com/danderson/netboot/blob/main/pixiecore/README.booting.md). My server works between two virtual machines on VirtualBox within the same subnet in BIOS mode.

However, when I moved to a real setup, I started my server, but my LattePanda SIGMA fails to receive the necessary information for booting.

On the server side, I get the following messages:
2025/03/24 10:33:10 [DHCP] Got valid request to boot 00:e0:4c:08:85:42 (X64)
2025/03/24 10:33:10 [DHCP] Offering to boot 00:e0:4c:08:85:42

which keeps spamming.

On the client side, I only see the message "START PXE OVER IPV4", and then the boot process stops with the error: "PXE-E16: no valid offer received"

I have enabled the "boot mode select with PXE" option in the BIOS, but it only allows UEFI Mode.

Has anyone encountered this issue before, and do you have a solution?