ZYXEL DISABLE NAT

Disabling NAT on the router via WAN connection will lock you out of the router.
Thus causing a hard reboot of the router is needed in order to gain access.

It is possible to disable NAT via telnet to router and copy ‘n’ pasting in below
command in one go : via WAN 

wan node index 1
wan node nat none
wan node save
sys save all
y

!
wan node nat option’s :

none = disables NAT.
sua = Share 1 NAT ip.
full = Assign multiple public ip addresses.