UDP windows target lost packet real time

Dear all, I am working with RTW and I want to send data from simulink to a server. First I try without real time packets and it was everything ok, but now something is wrong. I try to send 48 uint8 message and at the first time I receive 48 byte, but then I only can receive 8. I don`t know what is wrong because without real time it works fine.

Thanks