How do I fix my AT&T Gateway?

There could be a few things wrong with your AT&T Gateway, so we’ll walk you through some troubleshooting methods.
First, make sure that your Gateway is plugged in and that the power cord is securely plugged into the back of the Gateway and into an outlet.
Next, check to see if your Gateway has an Internet connection by going to Settings > Network > Status. If it says “Not Connected”, please try restarting your modem and router by unplugging them both from the wall for 30 seconds and then plugging them back in. Once they’ve both rebooted, try connecting to the Internet again. If it’s still not working, please contact us for further assistance.
 
Check here to fix your gateway error https://readus247.com/gateway-authentication-failure-u-verse/