In the router settings, he change the settings from ipv6 to ipv6 tunnel protocol.
After doing this, it lost the wifi connection (now the SSID is nowhere to be seen, others work fine).
The Power/dsl LED is flashing so it is powered but there is a problem with the dsl.
The Wi-Fi LED is off, using the wifi button does nothing.
At the moment he doesn't have an internet cable or an analog phone, so he can't directly change anything in the router.
So really changing from ipv6 to ipv6 tunnel protocol just broke dsl connection?