BGW210-700 replacement

Replaced my router gateway device thingy today easy enough with the ATT home app. ATT support sent it to me because I’m seeing max speeds of 200MB download and 80MB upload on Gb fiber. And I’ve been losing connection intermittently. So I replaced router and rebooted everything. Now I have internet connection but everything still sees the old SSID and uses the old password lol. Even Smart Home app. 
same speeds on meteor tests. 
but that old router is in a box by my front door. New shiny router is plugged in and running. But nothing can even ‘Discover’ the gateway/router. 2 hours with various ATT support is enough for a Sunday of non answers. 
I am assuming I could just do a manual change in the app but I find this really odd and even stranger that ATT support (at least 6 different people) had no intelligent ideas or explanations. 
many thoughts would be greatly appreciated. Seriously thinking of moving to Verizon for home internet. I work from home and I can’t have meetings dropping like this. And the support today was horrendous. Bummed yet feeling blessed :) TIA