I can't connect to my router's admin interface ?
Depending on your router's configuration, you might have to connect using a LAN port, and the client accessing the administration interface usually needs to be in the same IP range.
For example, if you need to connect to http://192.168.1.1 in order to access the management interface, your client PC needs to be in the range between 192.168.1.2 and 192.168.1.254.
There are a number of other troubleshooting steps you can take, here is a list:
Make sure you're using the correct IP address for the router, as well as the correct port (some use 8080 instead of the standard port 80). For a list of routers and their default IPs/passwords check our broadband hardware dataabse.
You can also often find your router's IP by simply typing: ipconfig in command prompt, and looking at the "Default Gateway" line.
Your client PC must be on the LAN side of the router (connected to a LAN port). You might want to try configuring it with a static IP address in the router's subnet (DHCP might not be configured properly yet).
Use a Cat5 cable to configure wireless routers - the wireless settings may not be configured correctly and wireless access to the admin interface may be disabled.
Simply reboot the router - it is possible that the built-in web server has locked/crashed, and you can't connect to it because of a temporary software issue that a simple reboot may be able to solve.
Reset the router to the factory defaults - NAT routers usually have a reset button, that when pressed for 10-30 seconds (while powering up/plugging in) resets the router to the factory defaults, so you can login with the default password, etc. Some may have a pinhole reset button that requires a sharp object like a paper pin to push. Just push in the button, then plug-in the device and wait for 10-30 seconds until the LED indicators show some change (they usually blink all together, in a different way than normal operation), then you can let go of the reset button. Note the procedure might be different for your particular router, check the user manual.
Disable web proxies - make sure Internet Explorer is not configured to use some type of web proxy for browsing.
Update firmware - sometimes a corrupt firmware can render the router useless. Try updating to the newest one from the manufacturer's website.
DHCP ? - NAT routers usually act as DHCP servers to serve multiple IP addresses to internal LAN clients. If you set your network adapter to "Obtain an IP address automatically" in the TCP/IP properties and your PC gets an IP address it is communicating with the router. This can be verified by dropping to command prompt, and typing: ipconfig. If the IP address is in one of the private ranges, usually 192.168.x.x, or 10.0.x.x, but not 169.*.*.*, then that indicates your client is able to obtain an IP from your router/DHCP server. You can also note the IP of your "Gateway" - that is the actual router IP you are connecting to.
PING the router - In Command prompt, try: ping 192.168.0.1 (substitute with the actual IP of your router from above step). If it works, at least you know that you have some connectivity to it and the cable is good. If you are also able to ping an external IP, like 184.108.40.206, for example, it indicates you are online as well.
Check cables and LEDs are you getting the link LEDs on both ends of all cables? You might also try different Cat5 cables. The router has a number of LED indicators as well, power, connectivity to the WAN port, etc.
Telnet ? - some routers have a serial port where you can connect directly (using a serial cable) and manage the router's settings via telnet. Even though it's a text-based interface, it does not rely on the network/IPs at all.
Note: If you are not sure of the default IP address, or username/password for your particular NAT router, you can look it up in our hardware database of over 3500+ routers.