Ok let me know if that works. I’m checking my working document now and yes I’ve definitely had problems booting UEFI clients with Option 43 present. I’ve been working on a document to describe configuring DHCP Policies on Windows DHCP and ISC DHCP on Linux to send separate options depending on the client type (option 43 for BIOS, and 66/67 for UEFI).
With Cisco DHCP, test first to see if removing Option 43 works. If it does, the simplest thing would be to have the Cisco devices forward DHCP requests directly to the Bare Metal Server, and remove options 43, 60, 66, and 67 from the Cisco entirely. The Cisco would then only provide IP/route/DNS information, and also forward the request to the OSD server. The OSD server should automatically provide the rest to the client. On the Cisco, in a global or VLAN definition, you’d add
ip helper-address 192.168.1.100
(with the IP address of your Bare Metal Server. You can use multiple ip helper-address lines if you have multiple servers).