The current Xfinity routers (end of 2017) do not support NAT Loopback and have no options for enabling NAT Loopback.
What is NAT Loopack?
NAT Loopback or Hairpinning is when Device_A behind a router tries to access another Device_B behind the same router by Device_B’s external name (e.g. domain name) instead of its local name (e.g. local IP address). Because of the way packets will leave the router and reenter, some routers disable NAT Loopback for security reasons.
When a router does not support NAT Loopback, a techie will have a problem if they are:
- hosting a home server
- using a domain name to route to the home server
- accessing their home server via the domain name while on the same network as the home server
- While home, access the server using the local IP address.
- Use a VPN to route traffic out of your home, which will then go back home and to your server.
- Buy a router that supports NAT Loopback. [link_1]
- Set up a local DNS server to change the public domain name to the local IP address.
- [link_1] http://opensimulator.org/wiki/NAT_Loopback_Routers