Friday, 7 October 2016

Optus - Sagemcom F@ST 3864 modem/router - admin username and password

The Sagemcom F@ST 3864 modem/router that is provided by Optus has an administrative interface that you can login to to access advanced features that aren't accessible via the the "standard" interface.

The standard interface is accessed via and allows access to basic settings such as wifi options without needing to enter a username/password

However, if you change the "loginuser=" value from a "1" to a "0" you get prompted for a username/password. Once you've entered the correct username/password you can then access more advanced features within the modem setup/config.

There are a number of forum posts stating some of the default usernames/passwords for this modem, but none of them worked for me, even after a factory reset. What I did stumble across though was how to definitively (and easily) retrieve the admin password for this modem;

  1. Open a web browser and go to
    You will be presented with a screen like the one pictured below;

  2. Right click in a blank area of the page, and select the option to "View source" or "View page source" (the wording might be slightly different depending on what browser you are using)

  3. This will load up all the html code used on this page. If you look towards the top of the page, you will see a line starting with "pwdAdmin = " - what is after this and contained within single quotes is the admin password that is set on the router

  4. You can then go to the URL and enter the username "admin" and the password from Step 3 above and you will be able to access the hidden/advanced menu options within the router


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  2. Looks like they have updated the firmware, this doesnt work anymore. Do you have an update?

  3. Step 1 brings up an 'authentication required' box asking for a username and password. It doesn't display the screen described.

  4. Hey Peter
    brilliant and so simple
    Works for me on F@ST3864V2 with firmware 7.276_F3864V2_Optus
    pwdAdmin = 'TWJqMm5yR0Y='

  5. Is there a way (in the new firmware) to get the admin option popup in the selection box?