SmartRoam+ is often enabled in the AP by default (dependent on the FW version and controller type).
What kind of devices are struggling to roam? It's important to remember that roaming decisions are made by the client device and can only be assisted by the network infrastructure.
It may help to enable 802.11k and 802.11r on the WLAN.
Also, this article may help: https://support.ruckuswireless.com/articles/000002277
Regarding the Apple device that struggles to connect; this is clearly a device-related issue and would therefore point to remedial action required on that device, including a factory-reset and reinstall of the OS or a faulty Wi-Fi adaptor.
Hope that helps,