It seems certain that 802.1ad devices do not populate the outer tag EtherType with 0x88A8. Special change is required in user data
to interoperate with these devices.
Assuming a Management VRF is configured with S-Tag:
20 and C-Tag:
100, edit the vrf_vlan section in / etc
/ config
/ gatewayd
as follows. Also, define resp_mode
to 1 so that the SD-WAN Gateway will relax its check to allow Ethernet frames that have incorrect EtherType of 0x8100 in the outer header.