This is the human-readable text accompanying the remote-invocation error code for a named group of FabricNetworks (VLANs) that UCS pushes as one set to the external VMM. Where the numeric code only tells you a remote call for that network-set push failed, this string is what actually explains why — often forwarded almost verbatim from the remote system's own error response. A typical value might read 'Unable to connect: connection refused', which for that network-set push usually means the far-end management service was unreachable at that moment.