Closing App Kills Network

Hi All,
I am seeing consistent network down in my host. Was wondering if it has to do with how my app is being killed.
So I have a server application listening on TCPSocket that is running and there is about 5 active connections. But whenever I close the app or kill it, my whole network will be dead not sure if this is application issue or my router issue. I then have to physically reboot my router.

In my code do I need to do anything to make it graceful disconnect before i Kill my app?