The reason that you can't talk to the F2424 is that the Jetpack has a firewall that blocks access to your F2424 from other devices on the internet.
You must configure the Jetpack's firewall to allow your remote device to access the PLC. I am not a Jetpack expert. In fact I rather dislike them for a long list of reasons and have helped several friends get Verizon to take the Jetpack back and return all of their money.
Google "port forwarding verizon jetpack". Now you will need to know the following:
1. The local IP address of the F2424. This is something like 192.168.1.5.
2. The external IP of the Jetpack. This is determined by Verizon. This IP may not be static and Verizon may change this IP when ever the Jetpack connects to their cellular data network. If the JetPack does not support a static external IP, take it back to Verizon as it is useless for remote access. Let's be optimistic and the Jetpacks static external IP is 207.1.2.409...
3. The port number that the PLC responds to. By default the port number is 9080.
Once you figure all of this out, you need to set up port forwarding on the Jetpack. Port forwarding allows requests made to the Jetpack's external IP to be forwarded to some device downstream of the Jetpack. to forward all internet Your PC will use an address like 207.1.2.409:9080 and the JetPack will translate these requests to 192.168.1.5:9080 downstream of the Jetpack and the PLC can handle the forwarded network traffic. Pretty neat.
Good luck,
Gary D*ckinson