Multicasting policy for Airplay over VDOM

NAT solved the issue

Goodmorning,

I'm having trouble figuring out the exact solution to this problem. Our setup is: Fortigate 100F with 2 VDOM (root & DEVDOM). DEVDOM has no wan uplink, instead it's uplink is routed over root using the VLINK interface. Our WIFI is set on ROOT (even for DEVDOM) which is then authenticated against a radius server to put them into the right VLAN. So let's say I'm dev, I belong to the V20 security group on AD, when I log into our wifi, I get VLAN 20 like DEVDOM. I put in place multicast policies that allow multicast traffic from one VDOM to another which works perfectly. So on WIFI, I'm able to discover all devices on the LAN side and am able to connect to them. The problem is when I start streaming, I get disconnected from airplay in 5 seconds. If I do not play anything, I stay connected to the device. Perhaps I'm forgetting a port or something but would appriciate help. thanks