Ensuring packet order in UDP

I'm using 2 computers with an application to send and receive udp datagrams. There is no flow control and ICMP is disabled. Frequently when I send a file as UDP datagrams via the application, I get two packets changing their order and therefore - packet loss.

I've disabled and kind of firewall and there is no hardware switch connected between the computers (they are directly wired).

Is there a way to make sure Winsock and send() will send the packets the same way they got there?

Or is the OS doing that?

Or network device configuration needed?