I got mine working using a different set of steps will post again later once I redo this so I can verify my steps.
Here are all the steps i did to get unraid working on my dell r410.
The dell server i fully updated using a windows 10 temp environment since you cant pull from the repository any more
All work done on windows 10 computer
Rufus version 3.13
unraid version 6.9.2
Downloaded unraid from website turned into iso
used rufus to to make bootable drive first using syslinux 6.04
grabbed ldinux.c32 file and copied to the side
used rufus to install unraid
Made the drive name all caps UNRAID
copied syslinux 6.04 to the new unraid drive
ran the make_bootable.bat
on dell bios changed usb to boot as harddrive
Boots with out any issues
If you get the error FATAL BONDING ERROR check and see if the drive is mounted, In my case the first usb unraid didnt like replaced it with another and now no issue.