Communication unexpectedly lost in both the terminal and while using QGroundControl

[AlexandraBarrett24]

Hello, I have been working with jMavSim and when I first load it, everything works fine and I am able to run commander commands to have the drone arm, takeoff, land, and disarm. However, after a few minutes, the simulator will announce "communication lost" and all following commands will not work. How do I ensure that this does not happen, or at least that I can regain connection without having to leave the program and rerun it?

Similarly, while using QGroundControl I am able to connect the simulator, upload a mission and run it, however sometimes in the middle of the mission the simulator will disconnect and I will be unable to reconnect it to QGroundControl without rerunning the program.