SSID not visible to S7 Edge

A

AC Question

I have searched but found no similar issue as what I'm facing. I got a new AT&T Galaxy S7 Edge that won't to see the wifi network at home. It sees my neighbors' networks but not mine.

I called AT&T Tech support and they tried a number of possible fixes but failed. I exchanged the phone for another S7 Edge but still having the same issue.

I'm using Sonic as the internet service provider with a Sonic router. The clowns at the AT&T store told me Sonic limits 5 devices per router. (I know for a fact that this is not true. I have 9 devices at home without problem).

I can manually add the network and the phone will connect (as verified by "Connected to XXXXX(SSID name)". But I will need to manually connect it each time I leave the network as it cannot be saved/remembered.

Please educate me if I need to change any settings on my phone or router. Thank you!

-Mike