How do you change the NAT settings on a bt home hub?

I was wondering how to change the NAT (network address translation) settings on a BT Homehub from strict to open.How do you change the NAT settings on a bt home hub?easiest way is to go into hub manager, select advanced, and when asked user name and password are both 'admin'. cannot find anything for nat settings, but might be under configuration and then firewall.