Fortigate 200E + SDN cannot access internet

Job ID: 32014373

Budget: $8 – $15 USD

Hello,
We have FortiAP, FortiSwitch and Fortigate.

It appears that out of 115 devices, only 2 or 3 can access internet.
I need help troubleshooting this ASAP. This should be fairly simple as it was working before.
Thank you