Frequently Asked Question

NAT Loopback Issues
Last Updated 9 years ago

Question : Why am I able to see using 3G or from another internet connection, but is unable to see when I am connected to the same WIFI network as the CCTV System ?
Answer :
Most likely, it's due to your router not supporting NAT Loopback.
This means that when you use the external IP/Hostname, e.g. cctv.dyndns.org, to access your CCTV system from the same network as it is connected to, your Internet Router doesn't know how to translate that into the internal IP address, e.g. 192.168.1.10.
Solution
1. Use Internal IP when access from same network, External IP/Hostname when access from internet.
2. Change Router to a model that support NAT Loopback.

Other information (Advance).
Occasionally users cannot log into web based applications using a URL that contains their external IP address inside their network. This is typically a result of security measures put in place by routers/modems, and referred to as a NAT (Network Address Translation) Loopback issue or constraint. This article will discuss what this means for ScreenConnect users and available configuration options.

What Is NAT Loopback?

Many routers/modems and some security tools prevent loopback connections as a security feature. This means that a machine on your local network (i.e. behind your router/modem) cannot connect to a forward-facing IP address (such as 208.112.93.73) of a machine that it also on your local network. Connecting to a local IP address (such as 192.168.0.2) of that same machine works fine.
If visiting the hostname or IP address brings up your router’s interface or an error message in the browser, you are experiencing a loopback error. Visitors outside your network should be able to still connect to any web applications hosted on this IP address; you just may not be able to see it yourself from within the server’s network. That article should help you fix the problem.

How Can I Bypass This?

There is often not a way to force a router to allow NAT Loopback, but here are the options we have identified that will allow both parties to connect to the web application successfully:
  1. Review your router settings to see if there is a NAT loopback on/off option
  2. Modify your Hosts File
  3. Utilize one of the other URLs internally, while using external IP outside of the network
  4. Set up a subdomain or dynamic DNS account
  5. Replace the router

Review Router Settings

Some routers will have an "enable NAT loopback" feature. Turn this on and you should be able to type in your external IP Address inside of your network. WatchGuard has an example of how to turn on NAT loopback for their devices.

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