...Help setting up separate networks for 2.4, 5.0 GHz devices

My landscape lighting and sprinkler systems (different companies) both require the use of 2.4GHz network to access.  All other devices in our house use the 5.0GHz band.   I believe my  set to default to 5.0 GHZ only, creating a conflict the landscape lighting and irrigation systems. 

I have  an Xfinity XB8. What setup should I use to resolve this?

thank you