To change the Wi-Fi name and password, I recommend following the instructions in the article linked below:

http://arris.force.com/consumers/articles/knowledge/G34-G36-Changing-the-Wi-Fi-Name-and-Password

Hi,

Tried using this link.

Supplied correct serial number of device and supplied correct WiFi SSID and password provided on device. But getting error message as below:

The information you entered does not match what is saved on the router. Please enter it again.

So please help me first to use default login name and password.

Thanks,

Ram 

Could you please let us know exactly where you're encountering this error? If you're trying it on a website, kindly share the URL you're using.

Getting eeror on this web site - http://192.168.0.1

If you are in the ARRIS surfboard login screen which indicates that you might have created a password for the login screen and On the G34, during the initial setup, you’ll be prompted to create a password for accessing the web interface.

If you’ve been using the web interface to configure your Surfboard gateway and happen to forget the password, I would recommend performing a factory reset on the device. This will restore the gateway to its default settings, allowing you to set a new password for the web interface.

Note: There is no default login for the web based interface (GUI)

For your reference , please refer the below link on how the first time setup works out 

http://arris.force.com/consumers/articles/knowledge/G34-G36-Web-Manager-First-Time-Login

Hi Support team,

You have recommended to perform a factory reset on the device , so as the gateway will reset to its default settings.

Is it possible to use reset button on device “holding down for few seconds and release the button” 

I tried this but did not work. After reset button holding/releasing, Shall I use default SSID name and pw given on device then change that using web GUI ??

Please confirm..

Regards.

You can reset the device by pressing and holding the reset button on the back for at least 20 seconds, then releasing it. The G34 will reboot, and once the LED flashes, it will be configured with the default settings.

After the G34 is back to its default settings, you can also change the network name and password using the Surfboard Central app on your mobile phone.

Please follow the steps provided in the links below to find the setup instructions for Surfboard Central and the steps to change the network name and password on the app.

http://arris.force.com/consumers/articles/knowledge/SURFboard-Central-Wi-Fi-Cable-Modem-Setup

http://arris.force.com/consumers/articles/knowledge/SURFboard-Central-Changing-the-Wi-Fi-Name-Password