The Roku must be connected to power through the Wall Outlet and not the TV USB port. If the power is not the issue, then it could be a defective router, a defective Roku unit, or both. I’d suggest contacting your ISP and/or the Roku Customer Support.
I’m into videotapes and old electronics stuff, including extenders, converters and analog 4:3 TV sets (which are obsolete these days), and Miss Bianca is my favorite character in Disney’s The Rescuers (1977) and its sequel, The Rescuers Down Under (1990). I am not a Roku employee, only a user like you. ~ Jordan
You've mentioned that your internet service provider is ATT. We would recommend changing your router settings for the 2.4 GHz band from g/n to b/g/n, as customers have stated that this helped resolve their issue. If you need help modifying your router, we suggest reaching out to ATT's customer support team. They will be able to assist you with that matter.
On some AT&T routers, the 5ghz band is automatically configured and managed to use wireless channels that are incompatible with Roku devices on the 5ghz band. (Roku cannot see or use wireless channels 52-140 on 5ghz band).
If you are unable to change the wireless channels on the 5ghz band, you will need to connect to the 2.4ghz band. To ensure you are able to connect to the 2.4ghz band, you will need to verify that the 2.4ghz band is actually on and broadcasting a SSID. (easiest way is to name the 2.4ghz and 5ghz SSID differently so you can easily see it). As mentioned, with some AT&T routers, will also need to verify b/g/n mode is enabled as well.
A further troubleshooting step you can try is to disable the wireless password and see if Roku device is now able to connect, both on 2.4ghz and 5ghz. (If Roku now connects, try changing your password to a simpler password that does not use any special characters).
Try connecting to a mobile hotspot if available to you. If you can connect to hotspot, then narrows problem to a network issue rather than a device issue.
Feel free to update posting or if you need more help.
Roku Community Streaming Expert Just another Roku user... I am not a Roku employee. Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102