How do you get to a DD-WRT router's configuration page? (repeater bridge)

You'll need to give your computer a static IP address on the same range as the DD-WRT router to be able to access it.

This can be done on either the ethernet or WiFi interface. Once the static IP address has been set to an IP address in the same range ( should start with 192.168.1.2 and end with 192.168.1.254 ), you'll be able to point your computer to 192.168.1.1 and access the DD-WRT configuration page.

The page you reference above, http://www.dd-wrt.com/wiki/index.php/Repeater_Bridge, suggests setting up a static IP address for the RB (=Repeater Birdge). It states:

Open the Setup -> Basic Setup tab

Connection Type will be: Disabled

Set STP for Disabled (Enabled sometimes can cause connection problems)

IP Address : 192.168.1.2 (Assuming Primary Router IP is 192.168.1.1)

Mask : 255.255.255.0

Gateway: 192.168.1.1 (again assuming Primary Router IP is 192.168.1.1)

DHCP Server: Disable

Local DNS: 192.168.1.1 (if IP of Primary Router is 192.168.1.1)

Assign WAN Port to Switch : Optionally enable this to use the WAN port as another LAN port.

Save

If you have done this, then the configuration page of your RB will be accessible at the IP address (to be typed in your browser) 192.168.1.2.

If you have not done this, then most likely your RB will have been given an IP address by your DHCP server, 192.168.1.1. To identify it, I suggest you use nmap, a precious utility which exists for all OSes. Then you can run a ping scan (in Linux and Unix you can do it as follows

  sudo nmap -sn 192.168.1.0/24

and there must be an equivalent command also for Windows, should you be on Windows), which will list all pcs which have joined your LAN. Your RB might identify itself easily, or, if you are unlucky, you may have to check the MAC address to see which one corresponds to the producer of your RB. At worst, you can just try to connect, through your browser to all IP addresses returned by nmap.