Abstract: Router circuit, provides Internet protocol (IP) address translation to enable connection or packet-level multiplexing over multiple single-user IP address account links. Connection-level multiplexing (CLM) provide between LAN and WAN addresses outbound packet transfer by replacing private packet source IP address and port number with said external IP address port number, and inbound packet transfer by replacing external packet destination IP address and port number with private IP address and port number. Look-up table provides bi-directional translation or effective multiplexing of IP addresses and port assignments for incoming or outgoing packets. Packet-level multiplexing (PLM) provides between LAN1 and LAN2 addresses outbound packet processing, wherein destination IP address and port number are replaced with external IP address and port number, and inbound packet processing, wherein source IP address and port number are replaced with internal IP address and port number.