Event 6273 Reason Code 8

Setup:

1. Server 2012 r2 as a Active Directory DC, Certificate Authority and Network Policy Server.
2. Auto enrollment of User, Computer and Workstation Authentication Certificates have been enabled and installed on all machines in the domain including the DC
   (PS: Not too sure which to use between Computer and Workstation Authentication certificate, so I selected both)
3. Unifi AP's as RADIUS clients broadcasting wireless network configured with WPA2-Enterprise.
4. A Grant Access Wireless Policy withConditions: Wireless Groups - Domain Users,NAS Port Type - Wireless IEEE 802.11 or Other, and Authentication Type -EAP, Constraints: Authentication Methods - Microsoft PEAP(CHAP and CHAPv2 unselected)

Problem:

1. I connect to the wireless network, and it prompts for credentials.
2. I use an account of authorized domain user and receive Can't connect to this network
3. Event viewer as two events with the same 6273 number: one with Account Name ofhost/computer.domain and the other with Account Name domain\user,both with Reason: The specified user account does not exist. 

Help.