回複：一個網絡連接問題，謝謝！！！

The modem has memorized the Mac address of you Laptop’s network card and will not authorize another one. But you can rerun the setup program from Laptop B while it is connected to the modem (this will make A out of picture). To solve the problem, you need a router (with wireless if you prefer) or a switch, connect the router/switch to Ethernet port of the modem and all computers to LAN port of the router/switch. In this way the number of computers connect to Internet at same time is limited only by the number of ports that router has (or as many as your routers limitation for wireless connection if it has any).

Good Luck!