Open a browser and go to http://192.168.1.254/ (or http://10.0.0.138)
Log in using your credentials. If you're on Infinitum (Telmex) the default user is TELMEX and the password is the default Wi-Fi password, also written on a sticker on the modem.
Otherwise, the default user is Administrator and the password is blank (i.e. no password).
Log into the modem's web interface.
On the sidebar, click on "Home Network".
On the sidebar, under "Home Network", click on "Interfaces".
Click on "Wireless Interface".
On the top right corner, click on "Configure".
Under "Configuration", enter a new network name/SSID on the form.
Under "Security", enter a new network password on the form.
Click on the "Apply" button
Log into the modem's web interface.
On the sidebar, click on the "Technicolor Gateway".
On the sidebar, under "Technicolor Gateway", click on "Configuration".
Under "Pick a task...", click on "Save or Restore Configuration".
Under "Backup current configuration", click on the "Backup Configuration Now..." button.
Shortly after, a user.ini file will be downloaded. This text file contains all of the (current) modem's configuration and setup.
Log into the modem's web interface.
On the sidebar, click on the "Technicolor Gateway".
On the sidebar, under "Technicolor Gateway", click on "Configuration".
Under "Pick a task...", click on "Save or Restore Configuration".
Under "Restore saved configuration", select a configuration file to restore (e.g. user.ini) and click on the "Restore Configuration Now..." button.
Note: You don't need to do this if you are able to connect via Telnet.
Export/backup the modem configuration and edit the file.
Under [ servmgr.ini ], search for TELNET state=disabled, update its state to enabled, and save the file.
Restore the updated modem configuration.
Connect via Telnet: telnet 192.168.1.254 or 10.0.0.138
Log in using your credentials (same as the web interface's).
To list out the current DNS servers enter: dns server forward list
To delete the current DNS servers enter: dns server forward flush
List out the DNS servers again to confirm they were correctly removed.
To set the primary DNS server enter (replace 0.0.0.0):
dns server forward dnsset add set=0 dns=0.0.0.0 label=None metric=10 intf=Internet owner=PPPTo set the secondary DNS server enter the previous command, updating the address.
To save the changes enter: saveall
To exit enter: exit
To verify the changes, log into the modem's web interface.
Under "Broadband Connection", click on "Internet".
Under "TCP/IPv4 Settings", verify the primary and secondary DNS addresses were updated.
Note: This may also be accomplished by editing the modem configuration and importing it.
Log into the modem's web interface.
On the sidebar, click on "Home Network".
On the sidebar, under "Home Network", click on "Interfaces".
Click on "Wireless Interface".
On the top right corner, click on "Configure".
Under "Security", for "Allow new devices", select "Allow new devices (via registration)".
Click on the "Apply" button.
Log into the modem's web interface.
On the sidebar, click on "Home Network".
On the sidebar, under "Home Network", click on "Interfaces".
Click on "Wireless Interface".
On the top right corner, click on "Configure".
Click on "Advanced WLAN settings".
Under "MAC Address filter" you can add new devices to the list.
Under "List of wireless devices" you can edit the access of the devices in the list.
Click on the "Apply" button to save the changes.
Note: The device name field has a character limit of 12. To work around that you can edit the HTML (via browser tools) or enter a short name, export the modem configuration, edit it with the desired name, and import it.