An authorization assisting device sends to the VBN server an authorization request for access to the WAN by a requesting user device. A registration driver has a set of assignable IP address ranges for multiple routing realms, and assigns an IP address to a user device from a relevant IP address range depending on a routing realm from which communication from the user device is received. The assignable IP address ranges include one or more authorization address ranges from which the registration driver assigns an IP address to a user device whose authorization request is received from the authorization assisting device. An authorization module processes the authorization request to generate an authorization response granting or denying access to the WAN by the requesting user device based on registration data in a registration data store and the information in the authorization request.