I have a lot of routers and I want to connect 4 LANs together with a router. I know routers have a WAN port. Is the wan port an Ethernet port? I have a diagram on what I want to do. How would you connect the LANs together? Would that be a WAN then?
Most home routers have 4 or more switched ports and a single WAN port. The WAN port is an ethernet port, and the router/firewall itself sits between the WAN and the local switched ports. Any of the local ports can communicate with each other in an unrestricted fashion. But for a packet to travel from the local ports to the WAN port or vice-versa, it has to go through the firewall, and is routed according to the routing rules.
If you want to simply join four LANS, and if they're all in the same IP range, you could simply choose one of them to be the "master" and then plug one of each of the other three's local ports into the local ports of of the master switch. You'd need to be careful to avoid duplicate IP's etc. And only the master router could be configured as the internet gateway, and be running DHCP services. So in effect you then have a single router with 12 or so distributed ports.
But if the LANs are in different IP ranges, then you'll need to have routes and routers between them. How exactly to do that is beyond the scope of a single question/answer.