I found my answer!
Yes! It is totally possible to do what I intended to do. I just hooked everything up and tested. It works!
QGC did have this:
I am writing this instruction only in case some other user is trying to do the same thing as I did:
- To avoid confusion, turn off your wifi during this set up.
- Hook up your Ubuntu machine and the Windows 10 machine using the ethernet cable.
- Go to your windows Network and Sharing Center. Under "Connections" it should show you the "Ethernet" one. Click on it to reveal Ethernet Status. At the bottom of that, click on "Properties".
- There you'll see something like this:
Click on the IPv4 and then click on "Properties" (highlighted).
4. In the properties thing that opens, Click on "Use the following IP address" and enter a meaningful IP (ex. 192.168.253.1) and enter 255.255.255.0 for the Subnet mask. Then click "OK" at the bottom of this properties section.
5. On your Ubuntu machine, go to your Network settings and pick Wired connections. In the settings for the wired connections, go to IPV4 and select Manual.
6. For Address, enter an IP differenet from the one you entered on the windows machine (ex. 192.168.253.2) and for netmask, enter the same 255.255.255.0. Then click "Apply".
Now you should be able to test the connection by typing "ping 192.168.253.x" from the terminal or command line (based on which machine you are using. If you are on the windows machine, replace the x in the IP with 2 and if you are on Ubuntu, replace it with 1. The point here is that you are meant to ping the IP address of the other machine. In my example, the Ubuntu one's address is 192.168.253.2 and the Windows machine's IP is 192.168.253.1.
Once that is set up, just follow this guide to make sure you are setting up QGC properly for the HITL simulation. Also, remember to pick the right IP address on the HIL config window on QGC. You have to change the "127.0.0.1" to the IP addresss of the computer that is running the X-Plane simulation.