Obtaining Router IP
From DD-WRT Wiki
There are certainly cases in which the router IP address may be unknown. If DHCP is disabled on the router, you will not be assigned an IP or a default gateway (the router IP address). The default IP may not be 192.168.1.1 or perhaps it was changed from the default. Without knowing the IP address, it will be impossible to perform firmware upgrades or make changes to the router settings. If you do not have the manual for the router, you can try looking up the router default factory settings online:
- factorydefaults.com - Not a comprehensive list, but has about 40 or so commonly used routers and has IP addresses for all of them.
- phenoelit-us.org - A very comprehensive list, but does not have IP addresses for all of them.
- answersthatwork.com PDF file - A fairly comprehensive list with IP addresses for many of the routers listed.
Once you know the default router IP, change the IP address of your computer to match the subnet of the default router IP (i.e. the numbers to the left of the .'s in the address). For example, if the router default address is 192.168.10.1, set the computer IP manually to 192.168.10.77 with 192.168.10.1 as the gateway. Power the router on with a continuous ping running in a command window:
ping -t <default router IP>
If you still receive no response, the IP address may have been changed from the default. Disconnect all other machines from the router and run arp in a command window to find out what the IP address is:
You should receive a response from the router even if it is on a different subnet than your computer. If you've received a response, the output will give you the IP address of the router. Once you have discovered the IP address of the router, change the IP address of your computer to match the subnet of the router as described above. You should now be able to ping the router and receive a response.