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 /
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.