In some situations when using a cellular modem, the Home Station computer may be connected to a network, which is protected by firewalls. In these instances the static IP address may be connected into a router, which splits the Internet connection between all networked computers. Under these circumstances, you may require the assistance of your IT department with the installation and network configuration aspects.
If the static IP is first connected to a router, the router must be accessed to allow for "port forwarding" at the Port you are using for communication. (Port 49200 is recommended for PCs using Windows 10). This function is largely available on most makes and models of commercial routers.
In the event that your network has strict firewalls, the security software may need to be accessed to allow for STS communication permissions. You may also have to set port rules and change firewall settings on your PC.