I'd agree with @Nolan Herring. I'd start with inspecting the firewall rules applied to the MX450; especially if there was a subnet change. The transferred rules may be applying to the incorrect subnet.

Greetings!Currently the Meraki MX devices do not display CDP/LLDP neighbor information on a per interface level. The best information available on the dashboard will show active interfaces (on Security Appliance -> Appliance Status page) and assigne...