I'm going to assume your WAN interface is statically configured, as opposed to PPPoE or something else. Options include: Get a spare switch, plug your Internet circuit, MX84 WAN interface and the router into it. Use an existing managed switch. Create a new VLAN. Put three ports into it in access mode. Plug your Internet circuit, MX84 WAN interface and the router into it. Ugly. On your MX create a new VLAN. Assign it a random subnet your not using. Put three LAN ports on the MX84 into that VLAN in access mode. Plug your MX WAN interface into one of these MX84 LAN ports. Plug your router and Internet circuit into the other two ports.
... View more