By default, Armored Core VI: Fires of Rubicon will try to connect to the servers any time you launch the game. To see how you can start off with the game offline when you boot it up on your PC, PlayStation 4, PlayStation 5, Xbox One, Xbox One S, Xbox One X, Xbox Series S or Xbox Series X, you can take a look at this tutorial from Seeking Tech.
1. For the first step, you need to head over to the System menu in Armored Core 6.
2. Once you get to the System menu, you need to select Network Settings.
3. On the right side of the same screen, you should see the Launch Setting, which is set to Online by default. It should show the following description:
Choose which mode (online or offline) to start in from title launch. Setting will be applied after returning to title screen.
4. To make sure that Armored Core VI: Fires of Rubicon boot up without having to connect to the online servers, make sure you set the Network Settings option in this screen to Offline.
5. Exit the System menu and then return to the title screen. You should now be able to boot up the game in offline mode.