Does gigapower modem broadcast a Hotspot?

AFAIK it does not. There should only be the one SSID for the active wifi.

Are you sure it's coming from the 5268AC?

Go here http://192.168.1.254/cgi-bin/wconfig.ha and disable wifi operation to see if the unknown signal stops.

Or just try and switch off the 5268 and see if the unknown signal disappears with it.

Thanks for the reply.

I have rebooted the modem and my named ssids disappear and so does the unknown signal. 

I am using a wifi analyzer that shows all wifi even the neighbors. I have even unplugged the modem and the unknown disappears and when it boots back up, it comes back on the same 2.4 channel as my other 2.4. 

I use a guest and the regular wifi that both I renamed and always an unknown signal right with them and same channel. The mac address doesnt match any of my devices.

Thanks

Appears to be a known "bug" but nothing to worry about see here

https://forums.att.com/t5/AT-T-Fiber-Equipment/POSSIBLE-VULNERABILITY-Pace-5268AC-Leaves-Wifi-Radio-On-With-No/td-p/5014959

Your wifi analyzer should be able to display the mac address of the hidden wifi ssid.  Compare that to the mac address of the gateway.  It should be nearly very close if the hidden wifi is coming from it, especially the first 6 characters.

Different mac address. this 3rd signal is equal in strength to my guest and normal network. whether weak in the back yard or standing next to the router. all three are equal. Same channel also.

I called AT&T and they didn't have a clue to what I was talking about. I have been very busy and haven't had a chance to delve into this and call tech support back.

It is a problem because it is unsecure and causes interference with my regular network