Windows Endpoint stop sending RADIUS Authentication

Question

Dear Team,

We have many endpoint enabled RADIUS authentication via our NAC Solution (Forescout). Around 2000+ Endpoints are authenticated via EAP-TLS Certificate but during Friday Morning, We noticed that many endpoint start failing authentication and try to use MAC Address to authenticated with our NAC which cause Authentication failed. I have raised ticket via Forescout Support and they said issue is coming from endpoint itself.

on Endpoint, We could see that Endpoint are not sending any authentication entity such as Username....etc for authentication.

Endpoint Error Message is:

ConnectionID 0x2

Identity - User -

Domain -

ReasonCode 0x70004 ReasonText The network stopped answering authentication requests ErrorCode 0x0 ExplicitCredentials false

Note: Issue is happen unexpectedly, Some Endpoints on the same switch are working as normal and re-enable (Shutdown and Undo shutdown) Switchport making endpoint work back.

Thank You and appreciate for every answer.