You're right that many devices don't choose bands very well, so you should use an access point that supports band steering if you want to do this. Pro APs will

You're right that many devices don't choose bands very well, so you should use an access point that supports band steering if you want to do this. Pro APs will support this and Broadcom-based AC consumer routers do also - need to read a review to know if a specific model works well though.