Agents may show as inactive within the CA client but are started and running on the server(s).
Investigation of the AgentServiceProxy.nptlog file shows a connection error similar to the following:
"Connection attempt [nprepository4[default]/servername] failed. NetProLib: Protocol::CConection::InitiateAuthentication - Unable to authenticate to spn: nprepository4[default]/servername Msg:netprolib:sspi::clientcontext::Initialize - The target principle name is incorrect.. Connection: 014e29f0"
"System.ServiceModel.Security.SecurityNegotiationException: A call to SSPI failed, see inner exception. ---> System.Security.Authentication.AuthenticationException: A call to SSPI failed, see inner exception. ---> System.ComponentModel.Win32Exception: The target principal name is incorrect"
If the Coordinator service is already running as Local System, try changing it to run as a Domain account to see if the errors change.
This error will also occur if the Coordinator is configured properly to run as Local System, but if the Coordinator server no longer has a trust relationship with the domain (the computer password is incorrect). Log out of the Coordinator and try logging in again. If you get an error similar to the following, the computer account password for the Coordinator server needs to be reset: