Hello @Learning
First of all I would like to recommend the next article to troubleshoot TLS/SSL issues with MAC computers: https://learn.microsoft.com/en-us/azure/active-directory/develop/ssl-issues
Regarding using only User certificates, it will depend on the usage. By default machine or computer certificates are used for network authentication, while user certificates are used for applications, EFS, and resources.
Computer and User Certificate Requirements
http://technet.microsoft.com/en-us/library/dd197531(v=WS.10).aspx
In addition, I'd like to share some related article for your reference:
Certificates
http://technet.microsoft.com/en-us/library/cc700805.aspx
How Certificates Work
http://technet.microsoft.com/en-us/library/cc776447(v=WS.10).aspx
Hope this helps with your query,
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