Just to add to the answer provided by cmr :  MX devices running MX 19+ firmware, MS devices running MS 17+ firmware and MS390/Catalyst devices running CS 17+ firmware will use the username admin and the password will be the serial number (Cloud ID) of the device (upper case letters and dashes).  All devices running other firmware versions will use the serial number (Cloud ID) of the device (upper case letters and dashes) as the username with no password.   https://documentation.meraki.com/General_Administration/Tools_and_Troubleshooting/Using_the_Cisco_Meraki_Device_Local_Status_Page ... View more