Very odd issue.
I have a mixed bunch of machines. I'm using netboot more often, and have made netboot files for most.
I cannot see any netboot image when I try to netboot an older 24" iMac (Mac 6,1). But I *can* see ALL the netboot images when I log in as admin and go to System Preferences, Startup Disk, on these iMacs. In addition, if I do select one as the startup disk, they boot perfectly. What's more, when I then reboot that one, and hold down the option key, I then see the IP address of the server that hosts the netboot images but still no enumeration of the 3 netboot images proper! Never seen that on any other model, so I am a bit baffled by this.
I can see all netboot images when I try a netboot from the NEWEST machines, 27" iMacs (and they boot and image just fine).
I can see all netboot images when I try a netboot from - gasp - the really old G5 machines (and they also boot and image just fine).
And yes, all one subnet. And yes, I take care to make the nbi on the matching hardware.
What am I missing here? Seems like I should be able to see the same array of netboot images form these "middle" machines. Firmware? Some obscure setting?