You can set QoS rules in the user profile of the SSID to limit how much traffic any one client sends at a given time. Keep in mind the QoS rules will only apply if there is contention for the network and will be split between all connected clients at the time. If you only want to limit iPhones, I would suggest setting up client classification to route iPhones to their own user profile with it's own QoS rules. If you can tell me which HiveManager platform you are using, I can provide a guide that reviews how to set up client classification.
This guide will walk you through how to determine which HiveManager you are using, for reference: https://thehivecommunity.aerohive.com/s/article/Which-HiveManager-Platform-am-I-using
