Regular Service Disconnection

My internet regularly disconnects between 12pm-2pm almost everyday, and a few times randomly through the day as well. It's not my personal devices, or the amount of devices I have connected, which is regularly 2-3 devices. I have restarted my modem/gateway/router, and devices multiple times and troubleshooted. I have had this problem for a while, but every time it happens I use att.com/support and it says my service is fine. It just crashes and pops back up. It's not just wifi issues. My husband's computer is hooked up with ethernet and it crashed. Again, I've had this problem for a while and we usually blow it off, but now that we're at home more it's annoying.
I finally got a random error code pop up yesterday "DSL Fail to Connect - ID:NAD-3305". I don't even know if it's presenting the right code, but this is what I got. I also notice the service light blinks green rapidly and usually it's back on soon after, but these quick service disconnections are inhibiting my work. It happened just writing this.

Does anybody have anything to suggest or and actual service rep to talk to? I keep calling 1-800-288-2020, but it tests my connection and says its working fine, doesn't connect me to a human, and ends the call.