UDP Communications Failing after a period of inactivity

I am using the TOP Server with the DNP Master Ethernet driver which is set up to accept unsolicited messages from my RTU using UDP. I have noticed that if the device does not send me any data for longer than 30 seconds, the TOP Server stops accepting data. I can still see the packets in a Wireshark. How do I fix this?

Please verify that the Firewall on this machine is not set to close UDP ports after a specified period of time (usually 30 seconds). This is a common setting to prevent an open port which could be used to attack a system when there is no data being exchanged over the port.