Can I use wireless by plugging in a network cable at the WAN port?

hello: I don't quite understand your question. If you just connect the router with wireless terminals to form a wireless LAN, it is not necessary. However, if you want the wireless terminal to access the external network through the wireless router, the WAN port must be connected with the network cable accessed from the network operator and set correctly. Chengdu Mingyi Technology Co., Ltd. Gold answers for you.