Hi. What's the name of the simulation software.
Right-click the start button and open Control Panel
In the upper right corner set "View by" to small icons (it may already be set to that)
Open Windows Firewall
In the upper left select Allow an app or feature through Windows Firewall
If you don't see the app listed click Change Settings
click Allow Another App
and browse to the executable file that launches the software and Add it.
You'll need to do this on both machines.
What's the name of the simulation software?
If the firewall is turned off Windows isn't blocking it.
How are these computers connected?
Are they both connected to a router, either by wire or wirelessly?
I am. There seem to be some difficulties with our network.
You'll need to set up port forwarding on the router so that it send traffic on port 500 to each computer.