I'll be very honest that this doesn't seem to me to be related to authentication itself, but something on your local network. It would be interesting to validate whether the mask and gateway are correct when you receive the IP.
If the problem persists, I suggest you open a support case.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
Please, if this post was useful, leave your kudos and mark it as solved.