NOTE! Using ISE 2.3p3 is not an option due to CSCvi94778 If you’re deploying a DNAC and you want to integrate with ISE, you might have read the following documents: Perform Post-Installation Tasks Cisco ISE Integration Limitations I did and ended up with this error in DNAC when adding ISE: Clearly this is a certificate error. The thing is that Cisco mentions that SAN (Subject Alternate Name) is essential for the trust between DNAC and ISE.