Try these troubleshooting methods if your Home Base cannot access the internet.
INSTRUCTIONS & INFO
Make sure your AT&T Home Base is powered on. Press and hold the On/Off button on the back of your device for three (3) seconds, until the Power light stays steady green.
For Ethernet, make sure that the Ethernet cable is securely inserted into the Ethernet port on the back of the Home Base and your computer (or other device).
For Wi-Fi: Make sure the Home Base is located in the general area of your Wi-Fi enabled device. Make sure that you are connected to the AT&T Home Base Wi-Fi network (e.g. ATT-HOMEBASE-XXX) and you are using the correct Wi-Fi Password.
Note: Your Wi-Fi password can be found on the bottom of your AT&T Home Base, if you have not changed it.
Move your Home Base to an area with a stronger cellular signal, typically near a window or outside wall.
Make sure the Wi-Fi light is on. If not, restart your Home Base by pressing and holding the On/Off button for three (3) seconds until all the lights turn off. Then, press and hold the On/off button for three (3) seconds until the Power light stays steady green.
On the AT&T Home Base Manager http://att.homebase (while connected to your Home Base), make sure the Internet connection button on the Home screen displays Turn Internet Off.
On the AT&T Home Base Manager http://att.homebase (while connected to your Home Base), go to Settings>Wi-Fi>Basic and make sure the Wi-Fi Broadcast is set to On.
On the AT&T Home Base Manager (while connected to your Home Base), go to Settings>Firewall>Mac/IP/Port Filtering and check that the IP and MAC Address of your device are not blocked by the firewall.