I have a Deco X3600 n, which for some reason the model list pull-down will not allow me to enter.  So ignore the information to the contrary above.

Although the default mode of this product is to offer both 2.4 and 5 Ghz streams, which works fine for most devices, I find that many products which claim to be only compatible with 2.4 GHz (802.11n max compatibility) cannot connect to it, seemingly forcing me either to run a publicly-visible guest network at 2.4 GHz-only that exists solely for these devices (not great) or downgrade the main signal to 2.4GHz for the entire house, which is not acceptable either. (WPA compatibility does not seem to be an issue).

One such 2.4-GHz-only product (the Ultraloq bridge) suggests as a last resort identifying and blacklisting at the router level the MAC address of any 2.4 GHz-only device from being allowed to connect to a 5 GHz stream on the router. Assuming this is even an option, it seems a bit ridiculous: if I have to go through this much work to get the router to connect to a 2.4 GHz device, this is not much of a "combo" stream. Given the number of smart devices that presumably will expect this type of compatibility, is there a better way to allow the router to just figure out when it is dealing with such a device and connect to it at 2.4 GHz without me doing a bunch of extra work? I recognize that these devices may be part of the problem but regardless of whose "fault" it is this is still a problem I feel that I shouldn't have to be dealing with.

I assume others have noticed and addressed this issue before. If you have suggestions or can better explain what might be going on, I would appreciate it.