Troubleshooting Tip: Unable to add an interface with zero references as a member to the FortiLink LAG

The FortiGate is configured with a FortiLink aggregation.

In the screenshot above, the WAN2 interface shows zero references. However, when trying to add it as a member interface in FortiLink, it does not appear in the selection.

CLI command:

FGT # config system interface

FGT (interface) # edit fortilink

FGT (fortilink) # append member
interface-name Physical interface name.
a interface
b interface
internal1 interface
internal4 interface

FGT (fortilink) # append member wan2
node_check_object fail! for interface-name wan2

value parse error before 'wan2'
Command fail. Return code -651

Solution:

Verify the IP mode of the WAN2 interface. If it is set to DHCP or PPPoE, change it to Manual, and it should then become available for selection as a FortiLink member.

CLI Commands:

FGT # config system interface

FGT (interface) # edit wan2

FGT (wan2) # set mode static

FGT (wan2) # end

FGT # config system interface

FGT (interface) # edit fortilink

FGT (fortilink) # append member
interface-name Physical interface name.
a interface
b interface
internal1 interface
internal4 interface
wan2 interface

FGT (fortilink) # append member wan2

FGT (fortilink) # end

Note:
Another possible reason is that the interface may be set as a heartbeat interface under HA configuration. This will also show the reference as 0 on the interface itself.