@Sebastian-Roth I agree, after looking at a dhcp booting process all weekend I can read the pcap like code from the matrix.
The requesting system is in BIOS mode so undionly is the proper boot kernel for it. I see the target requested the file size for undionly.0 from the tftp server at 192.168.1.133 with no second response from the fog server or no request for undionly.0 to be downloaded from the tftp server. This tells me the tftp server responded with “file not found” for undionly.0.