Hi @bluecat , as you’ve already stated, your safest bet here is to disconnect the WAN port. Or, is your ISP able to shut down their port connection to your MX? Then when done re-enable.
Darren O'Connor | uccert.co.uk
I'm not an employee of Cisco/Meraki. My posts are based on Meraki best practice and what has worked for me in the field.