Hi How to disable IPv6 on Homebox 6441?

Hi,

How to disable IPv6 on Homebox 6441? I have an issue with several mobile devices that are constantly dropping off from the wi-fi. Before asking for replacement of this box I want to try to disable IPv6 in WLAN in order to test if it is causing dropping off. Anyway, it makes no sense to use IPv6 in LAN and WLAN because it is using NAT.