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I'm adding another router to my home network to extend my WiFi range. (Linksys e2500.) I'm trying to change its IP from the default 192.168.1.1 so that it doesn't conflict with my primary (dhcp) router.

To isolate matters I've reset the router to factory settings, turned off my mac's WiFi and then connected the Mac to a Lan port on the router. Now I can view the router's admin page at 192.168.1.1. Great.

Now I change its local IP to 192.168.1.3 and leave the subnet as 255.255.255.0. The router reboots and after several minutes is inaccessible at any IP I try (still hardwired to the Mac with WiFi off). Ifconfig doesn't show the router and the only way I can get it back is to factory reset it again.

Anything I'm missing? Any settings I need to change on my Mac to be able to see the router?

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migrated from stackoverflow.com Mar 8 '13 at 18:50

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4 Answers 4

Ok I've figured this out (or at least, it's working again). Because I was turning off DHCP in the process of changing the router's IP, after restarting the router it was no longer assigning my Mac an IP. And since my Mac was disconnected from the main LAN, it wasn't registered with any router and therefore unable to see the router at 192.168.1.3.

The fix was to plug the new router into the main LAN after changing its IP. That allowed my Mac to get an IP address from the main DHCP router.

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IF two routers are in the same network, they need a protocol to communicate with each other. For home networks, I think RipV2 is the one to go with. You can't access the new router because your default gateway is set to your old one (which can't communicate with the new one).

At least that's what I think is wrong, I could be mistaken =) Hope this helps.

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So, in my scenario above, the only router connected to my mac is the new linksys one via ethernet cable. (The wifi is turned off.) And all I'm doing is changing the last octet of the local IP address. I understand that if I were changing one of the other octets it might be invisible because of the subnet, but that doesn't seem like the case here. –  Aaron Mar 8 '13 at 17:31
    
You can ignore the comment about RIP - it does not apply to most home routers. –  davidgo Mar 8 '13 at 18:58

Can you do a diagram (even an ascii art one) showing how you are linking the routers - this will help work out whats going on - as I can think of at least 2 valid configurations with different requirements.

Probably the best way to solve the problem would be the following config

                       INTERNET
                          |
                          | (wan)
                       EXISTING ROUTER
                        | (lan)
       -----------------+-------------------------------------------------    
       |                      |                  |                       |
       |(lan)                 PC1               PC2                     PC3
   NEW ROUTER

(The important bit is to connect the new router on the LAN SIDE, not the WAN SIDE, and ignore the WAN side on the new router.)

Assuming you have this configuration, then the most likely 2 reasons it is not working as expected are:

  1. 192.168.1.3 is being assigned as part of the DHCP range to a computer, and thus 2 devices have the same IP causing routing problems or
  2. DHCP has been turned off and your PC is no longer getting an IP address assigned over DHCP.

Maybe while setting it up, maybe hardcode all the IP addresses on the devices, ie ignore DHCP, then turn it on and define the range later on. (You don't strictly need to do this, provided your DHCP is correctly set up, and you avoid the range of IP's it can hand out, but it eliminates variables).

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I will also suggest to assign static IP addresses to routers and desktop PCs, possibly restricting the range of DHCP assigned IP addresses.

For example with a subnet like 255.255.255.0, you could set DHCP assigned adresses starting from 192.168.1.50 to 192.168.1.255 So adresses from 192.168.1.1 to 192.168.1.49 will be reserved for devices such as routers, desltops and network printers for example. This sometimes improve network perfomance a bit too.

Obiuosly the number of fixed IPs depends by the size of your network. You will need also to write down somewhere the list of ips assigned adresses.

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