how can I tell if the gateway is bad

Thank you for reaching out @musicrocky. We understand the importance of having a stable internet connection, and we'll be happy to assist.

We recommend that, you restart your Wi-Fi gateway or modem, or you can do this manually too. (The above-mentioned article will help you with the manual restart). 

Also, you can use your Smart Home Manager to restart your gateway.

1. Sign in to Smart Home Manager and select Network.
2. Scroll to and select Home Network Hardware.
3. Select Wi-Fi Gateway and then Restart.
4. Select Restart again.

After restart if the issue continues we suggest resetting your Wi-Fi gateway to original settings.

Heads up: Be sure to jot down your custom settings, like your static IP address if you have one, or your Wi-Fi network name (SSID). You can then change them back after the factory reset.

Hope this helps.

For further assistance feel free to contact us!

Mary, AT&T Community Forums Specialist.