I bought a Deco AXE5300 from Costco which I believe is the Deco XE75. It came with 3 units. In any case, I have a lot of devices that only work on the 2.4GHz network. The Deco app shows just one SSID for both the 2.4GHz and 5GHz network. There is an option to switch from 2.4GHz & 5GHz to 2.4GHz or to 5.0GHz only. When I select 2.4Ghz only, it fails, though. So my questions are:

1. When I have devices that just work on 2.4GHz, can I still use the combined 2.4GHz and 5GHz network with the same SSID?
2. How can I create a 2.4GHz SSID/network only?
3. If I do create such a 2.4GHz network/SSID, can I create a separate network/SSID for the 5GHz network?