My guess it has to do with the server and TLS versions being too far out of date, but I don't have all the info. What OS is the server (Server 2008, 2012, R2, etc.)? What OS is the client (Windows 10, 7, etc.)? In the mean time some places to check are below. Verify all the requirements of the Certificate https://documentation.meraki.com/MX/Content_Filtering_and_Threat_Protection/Configuring_Active_Directory_with_MX_Security_Appliances#Certificate_Requirements_for_TLS Assuming this is a Windows device, what error codes do you get on the client? https://documentation.meraki.com/MX/Client_VPN/Troubleshooting_Client_VPN
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