I recently had the same issue and fixed it by looking at the event log in windows.
Windows Start > type Event Viewer
Under Applications you will see the RASclient entries and error codes
I was seeing error code 720.
I made sure my config matched the instructions: https://documentation.meraki.com/MX/Client_VPN/Client_VPN_OS_Configuration
(IT DID)
What I actually did to fix my issue was head on over to Windows Device Manager > Network Adapters
Delete the WAN MINIPORT for IP as well as for L2TP.
Then above click the icon to scan for new changes. You will see them return.
Deleting the IP Miniport was the only thing that fixed this for me after I checked configuration, enabled firewall rules and looked at both logs in Meraki and Windows.
Hope it helps!
Tory
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