I have a main router which will allow me to have and automatically update two dynamic DNS addresses. I would like to add a third and I have several access points on my system also running tomato. I'd like to have one of the access points to serve by updating the third dynamic DNS. The problem is that as an access point the WAN port is disabled. I see an option to use an external IP checker(every ten minutes). Would using this option check and correctly update the WAN IP on the main router for the purpose of updating the third Dynamic DNS?