The MAC in question belongs to AXIS Communication device (a security camera or a door access unit). AXIS by default has "link-local" or "fallback" IP address setting turned on. This means, unless that feature turned off, the device periodically advertises its self-assigned backup IP address, and ready to use as a main address it in case DHCP server is not present on the network. That address is in APIPA range 169.254.x.x.  Since the DHCP or statically assigned main IP address and this fallback address are coming from the same device, Meraki catches that subnet mismatch in the logs. It is harmless, but you can turn off fallback setting on the camera, and it will stop appearing in the logs. ... View more