It seems that the Deco S4 v2.8 system automatically decides which band (2.4 GHz or 5 GHz) every device should use, and there is no option to place certain devices to use ONLY the 5 GHz, either by "pushing" them from the connected devices list or by setting an independent SSID for 5 GHz. I have noticed that even in close proximity, a device capable of 5 GHz will be served with 2.4 GHz by the Deco unit... and that shouldn't be the case.

Please add the capability to place Connected Devices to either 2.4 GHz or 5 GHz (by different SSIDs or else) rather than letting the app to decide. Including that enhancement in the next Firmware Release will be ideal.