Targeting the characteristics of small and micro enterprises, such as small network scale, few IT staff, and limited budgets, a lightweight architecture of "multi-WAN egress + core switch + access/PoE switch" is adopted. Office, guest, finance, and surveillance are isolated through VLANs, and the PoE switch directly powers APs, IP phones, and cameras without the need for additional power supplies. It supports ACL, QoS, and cloud management, and can later be smoothly expanded to a medium-sized campus.