pxe e53 error and option 60

I have zen 7 installed on a 6.5nw server, and I'm geting pxe e53 errors
when trying to boot to network. I've found a document that says I need to
set option 60 in my dhcp server since I'm running dhcp on the same server
as pdhcp. the problem is. that option is not there to apply. what am I
doing wrong?