two VOIP routers on one cable internet connection

  [DELETED] 16:57 06 Feb 2006

Hi, for complicated reasons my roomate and I have separate VOIP providers and two routers on one connection. Hers was set up first. When I set up mine, the VOIP works but I can't connect my computer to the net (that is, things work when the ethernet cable from her VOIP router is plugged into my computer OR it is plugged into my VOIP router). I cannot get internet on my computer by connecting it to my VOIP router, even when my VOIP connection works. Any suggestions?

  mgmcc 19:59 06 Feb 2006

How are the two routers connected to the Cable Broadband service? If you have connected a Network Switch to the Cable Modem's ethernet port and are then connecting two routers to that, it isn't going to work. That would have the same effect as connecting two computers to the modem - the ISP only allocates one IP address which will go to the first computer (or router) to connect and the second won't have internet access.

You would have to connect the second router to one of the first router's LAN ports so that its WAN IP address was actually a LAN address allocated by the first router. The routers would also have to allocate LAN IP addresses in different subnets (address ranges) or there would be IP address conflicts.

  [DELETED] 20:28 06 Feb 2006


Thanks for the response.

The connection is

Modem - Router one - Router two. So router two is connected to one of the first router's LAN ports.

I guess I will have to search and read more about WAN and LAN IP addresses and subnets. If anyone would like to take a shot at explaining or point me to a particularly good link, that would be appreciated.

  mgmcc 22:51 06 Feb 2006

If the two routers operate in different subnets (IP address ranges) or can be changed from their default settings to do so, you should be OK.

For example if Router one operates in the subnet, it will have an IP address of and will allocate addresses between and

If router two connects to router one and gets its WAN address from router one, the address will be in this subnet, let's say for example it gets a WAN address of

Router two now needs to operate in a different subnet for its own LAN IP address and the addresses it allocates to connected computers. For example, it could operate in the subnet (note the third octet of the address is now "1" instead of "0"), have its own LAN IP address of and allocate addresses between and

This means that router two would have a WAN IP address of and a LAN IP address of

...if that makes sense?

  woodchip 22:54 06 Feb 2006

You can only use one router at once. you have to unplug the one not in use

  [DELETED] 02:52 11 Feb 2006

I'm not entirely sure how, but I connected to both boxes and changed some numbers and bingo!

  [DELETED] 07:37 11 Feb 2006

Thanks mgmcc.

This thread is now locked and can not be replied to.

Elsewhere on IDG sites

Microsoft Surface Book 2 15in review

Illustrator Amy Grimes on how setting up her own eco-brand led to success with clients too

MacBook Pro keyboard issues and other problems

Test : l’enceinte connectée HomePod d’Apple