Set your device with a static IP.
Go to Admin Page of your router and configure under this:
Applications & Gaming > Port Range Forward
Ultimately you need to open ports:
TCP: 80, 443, 5223 (port number)
UDP: 3478, 3479, 3658 (port number)
Save and reboot the router.
If this not work, try to configure your device with static ip under DMZ of your router.