Even though you've tried Reset, try unplugging the gateway for 30 seconds, then reconnect. If there is no change, call 800.288.2020 and have support attempt to diagnose any line or hardware issues. They can dispatch a tech if needed.
Award for Community Excellence 2019 Achiever* *I am not an AT&T employee, and the views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.