PXE boot not working on some models

[smurray]

We have a very strange situation that I was hoping someone could shed some light on.

setup:
ZDM 7 IR4HP1
multiple VLANS

situation:

PXE boot does not work on any model workstation other than dell 760 if connected to the network in any valn other than VLAN1 where the server resides.

dell 760 can be PXe booted in any vlan
any other model machine can only be PXE booted in VLAN 1 which is where the PXE server is.

PXE debug log shows nothing recorded at all from machines other than the 760's

non-760 desktops will recieve the Proxy address of the PXE server, etc, but for some reason they show multiple gateways and the correct gateway is always last. the extra gateway numbers are coming from switches.

I have no clue as to why dell 760's will PXE boot perfectly every time and in any VLAN (they only get one gateway and it's the correct one) but any other type of machine will fail every time if they are not in VLAN 1

sometimes the non-760's will get PXE error E78 No boot file name ...
other times no PXE error but an error "could not contact the boot server"

HELP!