no, you should forward port 81 on your ADSL router.
In all this days I tried to do it ... but I can't. iptables or ipchain isn't correct?
you can also reach ISPConfig with the url : http://192.168.100.1:81
I still cannot reach this URL . . .
. . . and I still think there's something wrong in my settings of ISPconfig.
Thank-you all in advance for help.