Full support for ECC Certificates
Machines with an EEC client certificate can connect to the DP to download the content and install the agent but the client never registers with the site.
once i suspected the ECC certs I was able to find thread on technet which confirms the same issue I was seeing
Thank you for your feedback. We do support CNG certificates but at this time we only support RSA algorithms.
I will make sure this is added to our backlog for future consideration if it is not already there.
When I spoke to our CA team about this, it was their impression that ECC certs were supported given this entry supporting CNG certs and given that ECC would be a type of next-gen cryptography that has existed since Windows Vista: https://docs.microsoft.com/en-us/mem/configmgr/core/plan-design/network/cng-certificates-overview
However, after speaking with a senior engineer at Microsoft Premier Support, I'm being told that ECC is not supported and it is a known issue they hope to resolve in a future release. Disappointed to see this has not been made a higher priority for Microsoft.