@pqbrown iPhone 8 running latest iOS is the only one that stays on 5ghz. Macbook, ipad have not moved off of 2.4ghz since I turned smart connect back on and they're within 8 ft of the router.

@Carl Replying just to say I am experiencing the exact same problem with AX1500 firmware v1.0.2. 5ghz capable clients all connect when that is the only option, however 4/5 of those move and stay on...