Windows 8/Server 2012

[robinsmidsrod]

Your initiator-iqn and iscsi: target path doesn't look very proper. You initiator-iqn should look something like what you can see at http://ipxe.org/cfg/initiator-iqn and your iscsi target should look like what you can see at http://ipxe.org/cmd/sanboot.

Also I notice you specify the arch variable but never use it. Your module lines should look like this: module ${arch}/media/bootmgr bootmgr. There is also no need to specify net0 to when you're doing dhcp. The dhcp command tries all network devices in order until it finds one that has a response.

You might be suffering from the iBFT default gateway issue. Try set netX/gateway 0.0.0.0 before the sanboot command and see if it helps.

If you get an all-zeros MAC address something is very wrong. That should not happen. What kind of hardware are those machines using? It would be beneficial if you can capture the output of the ifstat command after having executed dhcp using the iPXE shell. That should give us more clues.

I'm going to assume you're using the latest version of wimboot and ipxe? A precompiled version of iPXE can be downloaded from http://rom-o-matic.eu/ and wimboot is at http://ipxe.org/wimboot.