PXE-E23: Client received TFTP error from server

PXE-E23: Client received TFTP error from server.  I get this error on some of my sete servers after selecting the x64 or x86 option in the F8 boot option menu.

more of the error, but I could get quick enough: 

- Failed to fetch file sizeFailed to read/process proxy response

- Failed to start the application

Any help on what is going on and a solution would be greatly appreciated.  7.1.8400