Handling DHCP timeouts in script

[digitalis99]

I've got an iPXE setup that is scripted to boot off an iSCSI target. I followed the examples for handling dhcp timeouts/errors, but I'm still getting random machines that timeout on the dhcp request and exit the script. The booting system displays "Connection timed out" and "No more network devices" errors and then exits back to the BIOS. I can't for the life of me figure out why. Can someone point out my error in the following script:

#!ipxe

:retry_dhcp
dhcp && isset ${filename} || goto retry_dhcp

set initiator-iqn iqn.2010-04.org.ipxe:${mac:hexhyp}

:iscsiboot
sanboot iscsi:10.0.0.1:::0:iqn.2008-08.com.target:prod-disk1 ||
sleep 3
goto iscsiboot