FreePBX in Standalone Classroom Environment

We are implementing FreePBX in 10 “similar” standalone classroom environments. None of these classrooms have any external connectivity whatsoever. We are simply using the FreePBX to simulate real world scenarios acted out between students and instructors. Again, all calls stay within classroom and do not have any external connectivity whatsoever; no Internet access.

I have completed handjamming the first classroom and want to use it’s configuration as a starting point for the next classroom. I built my second FreePBX server and “restored” the configuration using the “backed up” configuration from the first server. None of my devices/phones will connect.
No changes have been made to the phones that work on the first server. Even the IP of the FreePBX server is identical.

Any suggestions as to why the second server will not work?

Also, is there any way whatsoever that I can “activate” the FreePBX software without having Internet access?