I assume you are trying to make you ASA as your edge device and it should have a public IP configuration on its external interface but the Action Tech router in on the middle.
If that's the case i would suggest you to contact the router's manager [probably your ISP] and aks him to configure it to work in "bridge mode" that way it will be just a L2 device that will be placed between the ASA [now holding the public IP the router had] and the internet.
