Wifi connectivity is showing intermittent packet losses

[omer]

I am using Fortigate 100D Wireless Controller and FortiAP 221B. The issue which I am facing is that when I connect my laptop to the Wifi device a get high latency and intermittent packet losses in doing ping to my internal servers where as when I ping from my servers from local LAN system I do not get any latency and packet losses. I am facing this issue from quite a long time but found no resolution up till now. Can anybody help me with this issue?