Once I enable IPv6, I can no longer switch it off. I can change IPv6 between Auto, DHCP and Static, but once I try to set it Off, it says I need to re-login and before even storing the settings, it redirects me to login screen.
EDIT:
Indeed, the function that handles this, seems to have a void action on setting 'off' (ipv6Diag.js, line 253):
if(mode=="off")
{
alert(_T('_wizard','relogin_msg'))
location.replace("http://" + mainFrame._IPV4_IP[0]);
}
As a temporary workaround, one can issue from browser:
http://<yourNASip>/cgi-bin/network_mgr.cgi?cmd=cgi_set_ipv6&f_ipv6_mode=off