Great WAN Speeds... TERRIBLE Local Speeds?

A (local) good morning to all!

At our company, we have an SMB share that our employees use to share files and such. Long story short, on our LAN, the download and upload speeds to our share are fabulous.. on our WiFi, the speeds are absolutely atrocious. (See picture for comparison between our WiFi's and our LAN. Both are internal tests only).

We have traffic shaping on 2 out of 3 of our wifi networks, but it only affects internal to external traffic. Even on our unrestricted wifi, we have terrible local speeds (again, WAN speeds are great).

We have a Fortigate 90D at v5.4.5 and 2 FortiAP's 221C also at v5.4.5. I've run through the config but have not been able to find any anomaly. Has anyone seen or heard of what may be the cause?

Thanks,

Jordan