Cable Forum - View Single Post - Switched from ADSL to Cable

MovedGoalPosts · 29-03-2008, 13:50

If your router has an inbuilt ADSL modem, it won't work with cable. Cable has a standalone modem which needs an ethernet WAN (internet) side port on the router. Yes there may be 4 LAN side ports on your router, but that side of the router is effectively a switch. In other words anything connected on that side of the router can see everything else on that side of the router. The modem must only see one device connected to it, or the modem will not communicate properly. Worse your router would be trying to issue an IP address to the devices including modem, connected to the LAN side ports, when in fact the modem is trying to issue an IP to the single device it thinks it is speaking to.

You need a router that does not have an inbuilt modem, but which can connect to a standalone modem. These are usually marketed as DSL (not ADSL) or cable routers.

29-03-2008, 13:50	#2
MovedGoalPosts Inactive Join Date: Jun 2003 Location: 127.0.0.1 Age: 61 Posts: 15,868	Re: Switched from ADSL to Cable - do I need new router? If your router has an inbuilt ADSL modem, it won't work with cable. Cable has a standalone modem which needs an ethernet WAN (internet) side port on the router. Yes there may be 4 LAN side ports on your router, but that side of the router is effectively a switch. In other words anything connected on that side of the router can see everything else on that side of the router. The modem must only see one device connected to it, or the modem will not communicate properly. Worse your router would be trying to issue an IP address to the devices including modem, connected to the LAN side ports, when in fact the modem is trying to issue an IP to the single device it thinks it is speaking to. You need a router that does not have an inbuilt modem, but which can connect to a standalone modem. These are usually marketed as DSL (not ADSL) or cable routers.