New DSL router, Wi-Fi is spotty, packet loss on wired connection, can't get support

After having numerous problems with one side of our DSL, AT&T sent me a new router. Now Wi-Fi is spotty in my 1200 SF house and we've never had that problem before. I moved the router as much as I could with the length of the wires and it's the same. I also have frequent packet loss when playing games on a wired network connection.

Fiber service is less than half a mile from my house and a main N/S trunk line is 200 yards away from me. Meanwhile my signal comes from 30 year old copper lines underground.

AT&T support is no help at all because usually no one is available for chat or phone. When I finally find someone to speak to (chat NEVER works!) they don't understand a southern US accent and I can't understand theirs.

I'm sure Comcast/Infinity or a local ISP, CSpire, would be happy to talk to me and hook me up with fiber.