There is an atmel board that is controlling a few displays that we have. The company that we got the board for the displays from (that made the displays), gave us a data structure along with an IP and port to send the data to. Another software that is just a sort of simulator (just sends the data incrementally) was also provided.
We created two applications, one in C++ and one in C# to send the data. In both, we saw a lot of missed data packets but no packet was missed in the provided application. To debug, we monitored the data being sent using Wireshark.
In the provided application, udp packets were being sent and there was nothing else.
In the C++, application that we created, after every 2-3000 packets that were sent, there was a ICMP packet received that said destination port unreachable.
For the C# application, an ICMP packet was received after every 2nd packet.
What seems to be the problem here? Any idea.

We tried different frequencies at which we sent the data even coming down to 5 Hz. We also tried using a direct ethernet connection instead of using a switch. Getting the same response.