Hi @jvelasco , as @bbc states, you’ll be fine. Just as long as you replicate the features and services your MX was providing to the new firewall then normal service will resume.
Youll need to ensure that you open up the relevant ports on your new firewall to allow the Meraki devices to speak out to the cloud. This information can be found on n the Dashboard under Help > Firewall Info
Darren OConnor | doconnor@resalire.co.uk
https://www.linkedin.com/in/darrenoconnor/
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.