Perhaps the sender with the Livebox needs to adjust his Security settings ...
How do I change the security settings of my Livebox?
Remember: It is STRONGLY advised to use a wired ethernet connection to do this. If you change the settings using a wireless connection, you will be disconnected once the changes have been applied. If you have any wireless devices that are configured to connect to the Livebox already, please bare in mind that you will need to re-configure these devices again to connect to the Livebox.
* Log onto the Livebox configuration screen, either by opening a browser and typing in 192.168.1.1, or by double clicking on "Configure The Livebox" on your desktop.
* Type in the username and password for the Livebox (NOT your broadband account) and click OK.
The default values here are "admin" and "admin" for both the username and password.
* Navigate through the menu on the left:
Configuration -> Advanced -> Wireless
* You will be presented with four different "radio button" options:
o WPA or WEP security
o WPA security only
o WEP security
o No security
* Select the one that you want (or need) and then click on "Submit".
* On the next screen, click the "Apply the configuration now" button, and the Livebox will reboot itself. Once it has rebooted, your changes will take effect.