Ah, I didn't realize this was a PPPoE setup. I think you are right that in this case it would not work for the MX devices to be doing the PPPoE unless your ISP allows multiple connections under the same account (which is very unlikely).    In MX NAT HA with a VIP configured, both of the MX devices are active with their WAN IP's but the VIP is only active on the primary MX. So you will likely need a router/modem in front of the MX devices. It may be possible to put the MX devices in a DMZ from the router's perspective however which would get you close to bridge mode but still have PPPoE working.  ... View more