Hey @wick
Devices that end in -M come in Meraki Managed mode by default. You would have to migrate them first to DNA/CLI mode and then configure them as a monitor-only switch separately. Support can assist with Migrating to DNA/CLI mode.
https://documentation.meraki.com/MS/Deployment_Guides/Getting_started%3A_Cisco_Catalyst_9300_Managem...
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