Max Transit Duo - AP Configuration

What is the correct procedure to configure dual SSID WiFi access points where one SSID is using 2.4 Ghz only and the other SSID is using 5 Ghz only? I thought I had done it correctly and it was working but the 2.4 Ghz SSID AP keeps dropping of line and I have to reboot the Max Transit unit to get it back?