How are you assigning the 1.1.1.0/29 pool? Is it something that you have picked yourself? 1.1.1.1 is a public-ly routed subnet, so I would very much avoid using that on the WAN interfaces of the MX. Considering also that when Meraki Devices go offline and loose their Uplink Connectivity, they tend to be arp'ing a 1.1.1.1 address. If you do not have a public routed subnet assigned that you can use, try to stick to RFC1918 addresses.
... View more