How can I configure so that I can have access to my NAS world wide ? I tried different options but none of the combinations went successfully.
FROM WAN to LAN - allow any to a specific address from my local network, in fact is the IP of the NAS LAN TO WAN - allow any service, selected all
So you're actually on the wrong screen for this. To forward traffic from the WAN to your NAS you need to configure network address translation from Advanced > NAT Check out page 103 of the manual onwards for guidance ftp://ftp2.zyxel.com/ZyWALL_2_Plus/user_guide/ZyWALL%202%20Plus_4.04.pdf
Since you don't say what model of NAS you are using, what type of client you wish to connect to it and what protocols you intend to use, the only thing I can say for sure is that you're doing it wrong.
A better approach would be to set up a VPN on the Zywall and access your NAS through VPN.
