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LoopBack Issues

Loopback is necessary in some gaming applications. If your router does not support it, you can install an adapter.

Click the Windows Search button and type in "hdwwiz.exe".

Run the progam that appears at the top of the search list.

In the "Welcome to the Add Hardware Wizard", click Next.

Select "Install the hardware that I manually select from a list (Advanced)" and click Next.

Scroll down and select "Network adapters" and click Next.

Select under Manufacturer "Microsoft" and then under Network Adapter "Microsoft KM-TEST Loopback Adapter" or "Microsoft Loopback Adapter" and click Next.

Click Next

Click Finish

Click the Windows Search button and type in "Network Connections".

Run the progam that appears at the top of the search list.

Locate the "Microsoft KM-TEST Loopback Adapter" or "Microsoft Loopback Adapter" and open it.

Click "Properties"

Click "Internet Protocol Version 4 (TCP/IPv4) and then click Properties, or double click it."

Google "What is my IP" to get your public IP address

Enter your public IP address. The rest of the fields shuld be as shown below:

Press Ok to close all the network windows.

Right click and Enable the new adapter

Troubleshooting and Testing Loopback

If your router fails loopback, you can only run a viewer on  the server, even with the driver forcing loopback to work. Without loopback, getting the other PC's on your network to work requires hacks such as a change to the hosts file, and the use of a dynamic DNS system, which is beyond the scope of this article.

There is a built-in web server in Opensim we can use as a diagnostic. To test this driver, run the software and click [Start]. Wait for Opensimulator to boot up.

Now open a web browser and type in "" and it should show a web page. This is just a simple test of the local loopback to Opensim that is found in all PC's, and it must work if Opensim is working and your Windows firewall allows it.

The real test is to use http:// Public Ip and port 8002. You can get this IP address from That is also a good place to test your Port Forwards or uPNP settings.

My results:

    My PC (and yours) is localhost, so this should always work: http://localhost:8002

    Let us assume your Public IP is   So should work.  If it works, your loopback is fine.  If not, the loopback adapter is not running or is misconfigured.


If the "Public IP:Public Port" test fails, your loopback adapter is not working, or the Windows firewall is blocking port 8002, or Opensim is not running. The port can be changed in the advanced settings, so I would double check that the Public Port setting is set for 8002:

Sometimes the adapter/driver  just does not start by itself. You can right click the Network Icon and select "Repair".

Lastly, go check the settings in your adapter for TCP/IP Version 4 and make sure your IP address there is set to the PUBLIC IP address as seen by

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