How to create policy routing for traffic coming from the device.

The default route in Fortigate device leads to the operator, which has its own additional network protection. For example, it blocks Fortigate servers! I cannot change it. But we have the other operator on second WAN port. For one of VLANs I have defined appropriate policy routing. How can I define such policy routing for traffic from the "inside" of the device (communication with Forticloud, downloading antivirus definitions, etc.)? Which port is the source port for such traffic?