I don't know if it makes a difference but last year during one of the glitch weekends where people were getting kicked off and a loss, it was discovered that if you never went back to the console's main menu/desktop once you'd booted up FIFA it stopped it happening.
So far in 18, I've been doing the same thing. I've only had 1 disconnect in all 18 and I'd coincidently been back to my Xbox's home screen.
I'll forever do this just incase. This might have only worked for that one weekend but it's worth a shot.