Comcast causes port forwarding to be unsuccessful

The solution to the problem is that most inexpensive routers do not permit connecting to an external forwarded port from an internal IP. This applies to multiple computers, so if an old server has a rule for port forwarding, HTTP server forwarding, or DMZ creation, it must be removed before external access is possible. Another option is to use the same IP address as the previous machine, and the reason for not doing this is not clear.


After successfully setting up
port forwarding
on my Router, I found that the Router’s IP on the Modem’s subnet is

. When I visit

, it forwards to my local server, which is located at


I activated
Port Forwarding
on port 80 of my modem and assigned it to


Despite being “open”, the
public IP
cannot be accessed.

Am I doing something wrong?

After forwarding the Modem’s IP to the Router’s IP, which are and respectively, the issue persists. It seems that my public IP address is not the same.


Connecting from
internal IP
to an external
forwarded port
using home or inexpensive routers is typically not possible, as they do not support internal IP connections. This may result in it appearing as though the connection is not functioning when attempting to access it from within.

The type of NAT that was once referred to as hairpin NAT.

Request someone external to attempt to connect.

Frequently Asked Questions

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