From the release notes:
"Your card pool settings in automatch involve two numbers: the level you want to play at, and the pool range you're willing to accept. For example, you could set your own level to 8 and the pool range to 2, indicating you're looking for a game at level 6, 7 or 8. Setting the Pool Range lower means you're more likely to get exactly the level you want, but you're less flexible so you might have to wait longer for a match."
I have not found where to set the Pool range parameter. Where is it?
Found it.
Have to turn on 'advanced automatch' setting.