Hi, We just recently got the Shaw Advanced wifi Arris XB6.  My son just ordered some smart led light bulbs for his room. According to the Smart life app for the bulbs he needs to connect his iphone to 2.4 wifi then connect the bulbs. Can't get the bulbs to connect but then realized his ipnhone 6s is automatically connecting to 5g wifi.

How to do I get his phone to connect only to the 2.4 wifi and not automatically to 5g wifi signal as this router isn't like the old one that broadcast 2.4 or 5 and you decided what to connect too?

Thanks