Fastest Asus RT-AC51U Router Open Port Instructions

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Port Forward Staff
February 24, 2017 (Last Updated: ) | Reading Time: 5 minutes

Your Asus RT-AC51U router uses a firewall to help protect against malicious threats to your home network. The firewall does this by blocking unauthorized connections. This includes most online game and application connections. If you are playing a game online or program and it is not responding like it should or you are being continually kicked off, you need to create a port forward for that game and device.

In this guide I will be showing you how to properly port forward the Asus RT-AC51U router. I will walk you through each of the following steps:

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Step 1

It is important to setup a static ip address in the device that you are forwarding a port to. This ensures that your ports will remain open even after your device reboots.

This step is important because you want a permanent IP address in your device. If you do not set up a permanent IP address in your device, then when you device reboots it may get a new IP address.

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Have you considered using a VPN instead of forwarding a port? For most users, a VPN is a much simpler and more secure choice than forwarding a port.

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Step 2

After you have finished setting up a static IP address for the device you are forwarding these ports to, the next step is to login to the Asus RT-AC51U router. Did you know the Asus RT-AC51U router uses a web interface? This means you need to open a web browser to access your router management pages.

It does not matter what browser you decide to use, simply pick your favorite and open it up. Some of the more common web browsers are Chrome, Internet Explorer, and Firefox.

Once you have picked the web browser, open it up and find the address bar. The address bar is normally at the top of the page like the following image:

Image of a browser address bar
Browser address bar

Above is an example of what a web browser address bar looks like. Find the address bar in your router and type in your router's IP address.

The default Asus RT-AC51U IP Address is:

After entering the router's IP address into the address bar of the web browser, simply click the Enter key on your keyboard. If all goes as it should have, you will be given this box:

router login screen
This is the login page from your Asus router.

There are two spaces on the login page for the username and password. Enter the router's username and password here and press the blue Sign in button.

Trouble Logging In?

If you are having trouble logging into the web GUI/router setup pages, here are a few things you can try:

  • First, I recommend trying other Asus usernames and passwords. If you have a different firmware version you could also have a different username and password. Here is our list of Default Asus Router Passwords.
  • If the first option did not work it is because you changed the username and/or password in the past and don't remember. I now recommend guessing or trying to crack your username/password. Need some help? Use our Find Password App. This handy little app does all the heavy lifting for you. It goes through thousands of different possible combinations for you. Learn more about it on this Router Password Cracker page.
  • Finally if neither of the above options worked, it might be time to think about resetting your router. A reset like this is a big step and should not be taken lightly. Every personal setting you have changed in the past is erased. I strongly recommend trying other methods of troubleshooting before you continue. Learn how to reset this router on our How to Reset a Router page.

Step 3

You should now be on the first page of your web GUI. It is time to find the port forwarding section of the router. I will show you exactly how to find it, let's start on the Network Map page of the Asus RT-AC51U router.

router setup
This is the setup page from your Asus router.

On the Network Map page of the router look in the left sidebar under the Advanced Settings heading. Choose the link titled WAN.

Then at the top of the page you should see a row of tabs. Pick the one labeled Virtual Server/Port Forwarding.

router virtual server screenshot
This is the virtual server page from your Asus router.

You should now be on a page like the one you see above.

Make sure the radio button labeled Enable Port Forwarding is clicked to Yes.

Step 4

Here are the ports to forward for Xbox Live:

  • TCP Ports: 3074
  • UDP Ports: 3074

If you are looking for the ports for a different application you can find it by either:

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Create a name for this forward and put it in the Service Name box. The name is only used as a reminder and has no effect on the port forward.

Enter the ports to forward into the Port Range box.

The ports can be entered as a list 23,24,25, a range 500:600, or a combination of both 23,45,500:600.

Enter the IP address to forward these ports to into the Local IP box. If you are forwarding ports so you can run a program on a device other than your computer then you can enter your device's IP address into that box.

Select the required protocol for these ports from the Protocol dropdown box.

Click the + button when you are all done.

Once you have finished entering the data in your Asus RT-AC51U router, make sure to click the Apply button under the port forwarding list.

Are Your Ports Open?

After you have finished, it is an extremely good idea to check to see if the ports are forwarded properly. To do this I recommend using our Open Port Checker. It is part of our FREE trial version of the Network Utilities Bundle. What makes our Port Checker better than others on the web is that we use a local application to see if the ports are listening. This gets rid of the possibility of a false positive. Our Port Checker is GUARANTEED to be correct.


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Wait... you're looking for more router setup guides? You want to know how to create a truly secure home network? How do you change the WiFi channel? I got you covered, check out for all things router setup related.

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