I was hoping that this had a better solution since originally opened but looks like the MX only supports eBGP when configured in One-Armed concentrator mode.   NAT Mode iBGP establishes relationships over autovpn and will establish and exchange routes between: A BGP peer acting as a One-Armed Concentrator in the DC and- A NAT mode MX. eBGP peer relationships are not available for MXs operating as NAT mode VPN concentrators and are only supported on One-Armed Concentrators.   https://documentation.meraki.com/MX/Networks_and_Routing/BGP ... View more