The present invention relates to an access unit for coupling a plurality of subscribers to a data communication network, and comprising an auto-configuration control unit adapted to learn, from first auto-configuration data issued by an auto-configuration server and transiting through said access unit towards a particular subscriber coupled to said access unit, a particular network address as being dynamically assigned to said particular subscriber.An access unit according to the invention is characterized in that said auto-configuration control unit is further adapted to learn, from second auto-configuration data transiting through said data communication network, said particular network address as being newly assigned to another subscriber, and in that said access unit further comprises an auto-configuration preemption unit coupled to said auto-configuration control unit, and adapted thereupon to issue an auto-configuration control signal towards said particular subscriber, whereby a new auto-configuration session is initiated between said particular subscriber and said auto-configuration server, and further whereby a new network address is dynamically assigned to said particular subscriber.