To change an entire subnet of SLAAC-configured workstation addresses, the best method is to change the address prefix in a router. SLAAC (Stateless Address Autoconfiguration) relies on routers to advertise network prefixes using Neighbor Discovery Protocol (NDP). By changing the address prefix in the router, it will advertise the new prefix to all SLAAC-configured devices on the subnet, causing them to generate new addresses based on the new prefix. This method is automated and efficient for updating addresses across all devices in the subnet.