Hi There can anybody please help

I am trying to setup a site to site VPN connection with my office we are using Vigor 2700 routers, we have 10 remote sites, i have sucessfully managed to setup site to site links with 9 of the remote site but i am having trouble with one site that has a dynamic IP address.

Is it possible to use a domain name as the peer identity on the vigor as i only see an option for IP address?.

Our Fire wall at the main site supports all these kinds of authentication but cannot see any possible way other than IP on the Vigor.

Thanks

John