I got Smart Connect (Tri Band) working on all my devices by resetting the SSID = changed SSID to another value and then changed it back on the screen where you can enable or disable Smart Connect.
I also made sure 2.4 GHz was selected in the dropdown before selecting the 'button' to enable Smart Connect (one would think this should not matter).
Now that I have it working for everything, Smart Connect is selecting the 5 GHz band for only 3 of 11 wifi devices that are actively connected...
2...
Asus RT-AC5300 Smart Connect on or off?
I also made sure 2.4 GHz was selected in the dropdown before selecting the 'button' to enable Smart Connect (one would think this should not matter).
Now that I have it working for everything, Smart Connect is selecting the 5 GHz band for only 3 of 11 wifi devices that are actively connected...
2...
Asus RT-AC5300 Smart Connect on or off?