From the log that iVentoy doesn't receive the tftp request packet from the 2nd PC.
You can use tcpdump to capture all the packets during PXE and then to check that whether there are the TFTP request packets from the 2nd PC in the captured result.
You can use tcpdump to capture all the packets during PXE and then to check that whether there are the TFTP request packets from the 2nd PC in the captured result.