
Many users and subscribers are complaining that they are having trouble with an error called ‘Gateway Authentication Failure’ while trying to connect to the internet with a U-Verse modem, there can be many reasons for this issue, one of the main reason is the configuration of settings of the modem.
During installation and configuration of the modem, it may happen that the user might have configured the modem in the wrong manner, it can be improper assigning the IP address, authentication failure, or wrong gateway, etc. sometimes these errors could be irritating and time consuming.
If these are set correctly, then it could be other reasons, what are those and how we can solve it?. Let us understand and find it below.
What causes the Gateway Authentication Failure?
There can be several causes that create a problem when you connect to the network like default gateway is not available, 502 Bad Gateway, and so on.
The main cause behind this error is that some of the launch configurations are buildup by the modem and it increases the loading time at the initial stage and if the loading configurations get corrupted due to sudden power shutdown, it will block the modem from communicating with the servers and hence the users face the error of Gateway Authentication Failure.
Now you know how the error occurs, now lets us move towards the solution for this error through our step by step guide.
Solution 1: Check the Router Network Connection

Sometimes it may happen that the network cable may not be properly plugged-in into the network port, that may lead to an interruption in the network connection, even a network cable into the wrong ONT port may disrupt the internet network connection.
Of all these, perhaps the most common is the cable issue. sometimes we forget or seems to be dumb to check the network cable which is lying out from the ONT port or loose cabling.
Even if it is plugged into the right ONT port then ensure that it is firmly connected to it, sometimes a loose connection can also disconnect the incoming network. Check if the issue persists, if yes, then hop to our next solution method.
Also Read: What are the Ways to Fix “DNS Server Unavailable” in Windows 10
Solution 2: Power Cycle the Router
Another main reason for the error of ‘Gateway Authentication Failure’ is that the router buildup corrupt internet cache and preventing the users from establishing a secure connection with the servers.
so it is very important to delete the buildup internet cache by power cycling method with the router. let us check step by step below.

Turn off the router by removing the power cable from the power socket.
Then, plug out the network cable from both ends of router and service provider modem and wait for atleast 5 minutes.
After a few minutes, plug in the network cable and power cable into their respective ports and sockets and swtich ON the power button of the router or modem.
After doing all this activity, check if the att Gateway authentication failure occurs again, if it persists, then go with our next solution method.
Solution 3: Reset the Browser cache
Sometimes browser cache may create the issue of internet connection problem hence it highly recommended to reset the browser cache and cookies in the chrome application.
So what are the steps for resetting the browser cache, are mentioned below step by step.
Step 1: Open the chrome, at the top right you will see three dots, just click More .
Step 2: A drop down menu will open, select the setting option.
Step 3: At the top, in the search setting type ‘Clear browsing data‘. To delete everything, select All time.
Step 4: Check all the option of ‘ Browsing history, cookies and other site data and Cached images and files,”.
Step 5: Once done, then hit on clear data option.
and, later check for the error.
Solution 4: Reset the Router’s configuration
If you are still here, then it means your problem is not yet resolved, you don’t have to worry, this solution method is the most effective which will definitely help you to solve your issue of att Gateway authentication failure.
Note: that resetting your router or modem can vanish all configuration that you made during the router setup.
There are two methods from where you can reset the your router:
Give a hard reset to the router: that means your router is having a reset button behind, you just need to press the button with the help of little pin as shown in the picture below for 20 seconds, which is also called hard reboot to the router and wait for 5 minutes so that the router gets reset and build a connection with its servers again.
Soft Reset through Browser: that means you have another option of resetting the router that is with help of any browser.

Step 1: Open any internet browser and type the IP address 192.168.1.? in the address bar (IP can find at the back of the router or in the manual).
Step 2: Enter your credentials to login and navigate to the setting tab.
Step 3: Then select ‘Diagnostic‘ and click on Reset options.
Step 4: You will get ‘Reset to factory default state‘ select it and wait for few seconds.
Step 5: Once the modem gets completely reset then check for the Gateway authentication failure att issue.
Bottom Line
If you don’t find the solution with the first two methods of checking the router cable and power cycling the router, then we must assume that the issue is critical and it’ll better if you reset the router or modem as per our third method of Reset the Router’s configuration, if that also doesn’t help then you can visit MyATT page follow their step by step guide and at last if not resolved you take support from the service provider.
We assure you, by opting for our methods you will definitely get the positive results with your router and Do comment in the comment section for your any queries related to Gateway Authentication Failure.