Failing to download via http 1 out of 5 times.

[silver310]

Hi, I've set up an iPXE server, all file downloads are done via http.
The problem is that every 1 out of 5 times it'll fail to download the file, it'll show me an error "couldn't retrieve file" and reboot, if i try to boot it again it'll download the same file successfully (trying after 30 sec).

I don't know if this is an iPXE issue or a problem with my server.
I am running the latest version of iPXE on a Centos 7 server.

How can I file out where this problem is coming from?

Also, is it possible to return to the main menu after that kind of error?
In my menu.ipxe file i have
:some_entry
kernel some_kernel
initrd some_initrd.img
boot || goto failed

:failed
echo Booting failed, returning to main-menu
sleep 5
goto start

where start is my main-menu, but this doesn't work, it just reboots.