Hey @Suppositori,
I do not play Star Wars Battlefront but do own a Xbox.
Most of the times when you get an errorcode you can check Microsoft for solutions.
Find your error code | Xbox Support
In this case I found a workaround for the code 918 somewhere else:
To fix the Star Wars Battlefront 2 error you could try to:
Close the game down fully.
Reboot the game.
Try to sign in again.
Repeat the process until you log into the game successfully.
Or You could check EA Twitter for extra information: (EA Star Wars (@EAStarWars) / X (twitter.com)