This object records the internal VPN pool address that had been assigned to the peer at the time of the failure, or explicitly 0.0.0.0 if the failure happened before any address was ever assigned, per the desc. An admin can use a 0.0.0.0 reading here to immediately know the failure occurred very early in negotiation (before address assignment), versus a real internal address indicating the client got further into setup before something else went wrong. Seeing an assigned address like 10.50.3.12 tied to a failure narrows the problem to something after address allocation, such as a post-connect authorization check.