Understanding Router/gateway

[jdelrio22]

Recently I moved my router and modem from one room to another. I was having problems at first getting a connection when suddenly the modem was able to complete a connection. In the previous room, the router was connected to the modem via Wan to Wan connection.

When I moved everything to this room, the connection would not work for internet so I randomly connected my router to the Lan1 connection on my modem. All devices have internet access now through the router.

My router instantly changed its IP to prevent a conflict with a modem but I need help understanding why this worked. I am a puzzled because I have always made a connection to the WAN and not to LAN for Modem to Router connections.

 

[kornphlake]

In the old days of high speed internet a modem was only a modem and only provided one public ip address to one device, a router was needed to share that connection with more than one device. As technology has improved and prices have come down modems have become more sophisticated and may include the basic functions of a router, which would let you plug the modem into a switch instead of a router when more than one device needs internet connectivity. When you plug your modem into the router's lan port you're using the router as a switch and the modem is serving dhcp addresses.

If you were able to use the WAN port on the router in one room you should be able to use the WAN port in another room as long as you didn't change any of the settings in the router when you moved it. I suspect you have an issue with some of the cables or connectors that are the real source of your confusion.