Click on the link below:
http://support.linksys.com/en-ca/support/routers/E900
Then select hardware version 1 and click the download link:
A firmware file will download and you need to save it somewhere you can find it again for upload to your router.
Login to your router by clicking the link below and user credentials username "admin" and password "admin":
Click the Administration tab, then click the Firmware Upgrade page.
Click Browse, then go to the location where you saved the upgrade file.
Select the upgrade file, then click Start Upgrade and follow the onscreen instructions. The upgrade process begins, and a progress bar appears. When the firmware has been uploaded, a new page opens with an “Upgrade is successful” notice, and the router reboots.