I understand this may be due to our using syslinux 6.0.3 (latest version), and the com boot files there changed between versions 3 and 5.  Since we upgraded to the latest version to fix bugs, we can't go back to 3.08.  We may need to do gPXE chaining, which I’m looking into. 

1. Does anybody know if ESXi 6.0 is based on syslinux 3.08? 

2. What are your current scripted install (kickstart) servers running for the version of syslinux?