The Linksys EA4500 router ships with a default username, password, and IP address. To access the router, open a web browser, go to the address bar and enter 192.168.1.1, which is the IP address common to most routers.
Then enter admin as the default username and admin as the default password (the password is case sensitive).
This device's model number is EA4500, but it's often marketed as the Linksys N900 router. Also, even though it's available in two hardware versions (1.0 and 3.0), both use the same default information above.
If the EA4500 Default Password Doesn't Work
A default password fails because someone changed it. Changing a password to something more secure (especially when it's really simple, such as admin) is important for the security of your network.
If the default Linksys EA4500 password doesn't work, reset the router to its factory defaults:
Power on the router, then turn it around so you have access to the back, where the cables plug in.
Use a small and sharp object such as a paperclip, to press and hold the Reset button for about 15 seconds, until the power light flashes.
Unplug the power cable for a few seconds, then plug it back in.
Wait 30 seconds or so for the router to boot back up.
Log in to the Router
Now that the N900 router is reset, log in to it from a web browser:
Go to the address bar and enter http://192.168.1.1.
The router and the device you use to access the router must be on the same network. If the device is a phone or tablet, connect to Wi-Fi.
Enter the N900 default router information (admin for both username and password).
Change the default password to something other than admin. This step isn't necessary, but it may as well be. You can store the new username and password in a free password manager to avoid ever forgetting it.
After the router is reset, any customizations you made are deleted. This includes the wireless network password, SSID (service set identifier), and DNS (domain name system) server settings. Re-enter that information to get the router back to how it was before the reset.
To avoid losing the configuration information in case the router is reset in the future, back up the configuration to a file. Use this file to restore the router settings. Page 55 of the user manual (linked below) shows how.
What to Do When You Can't Access the EA4500 Router
If you can't get to the EA4500 router through the 192.168.1.1 IP address, it likely was changed to something else after it was first set up.
The router doesn't need to be reset to get the IP address (but if you did already reset it, the default address should work). Instead, find out the default gateway that a computer connected to the router is using.
Linksys EA4500 Firmware and Manual Links
Visit the Linksys EA4500 N900 support page to find the resources Linksys has on this router, such as updated firmware, a user manual, FAQs, and more.
The user manual is a PDF file; use a PDF reader to view it.
When downloading the firmware for the EA4500, download the right one for the hardware version of your router. The download page has sections for versions 1.0 and 3.0. Each section contains a separate link to the firmware. If you're in the United States, read the Important note on the download page.