Since you have the service published on the internet and the clients are accessing it via the DNS that is configured on their internet router.
The only way I can see is if you "force" the machine to use its internal DNS instead of the DNS that is configured on their router, or if you do not publish the service via the internet if that is a possibility.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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