I would check the interface settings and remove it's role as a FortiLink:
conf sys int
set fortilink disable
Then, I'd check if the DHCP server is restricted to only serve certain devices identified by a VCI string:
config system dhcp server
set default-gateway 169.254.2.1
set netmask 255.255.255.0
set interface "port18"
set vci-match enable
set vci-string "FortiSwitch" "FortiExtender"
If so, just set "set vci-match disable" to fix.
"Kernel panic: Aiee, killing interrupt handler!"