The X.509 certificate chain used by this service contains certificates that aren't required to form a path to the CA.
At least one of the X.509 certificates sent by the remote host is not required to form a path from the server's own certificate to the CA. This may indicate that the certificate bundle installed with the server's certificate is for certificates lower in the certificate hierarchy. Some SSL implementations, often those found in embedded devices, cannot handle certificate chains with unused certificates.
Remove unnecessary certificates from the certificate chain.