Unlimit Clients IP Address

Dear Expert . I install my freeeradius server and put the server at ISP. I try to access the server by router (WRT54GL+coova). I can see the login page but when I try to login the login failed. I think the problem is freeradius clients that fix on client.conf that fix the ip. But I can not fix ip cause I get the random ip form ISP, it 's not real ip. How do I set unlimit clients ip address on clients.conf? if it 's not possible , which radius software that support unlimit clients access? Thank you forwards and Best Regards. Chuan