Something messed up with connection between controllers and system?

So my controller won’t work if it’s further than about 6” from my Xbox. I figured it was the controller so I bought a new one, it does the same thing. I’ve tried synching them again, it still doesn’t work. So I think it’s something I’m the console itself. My brother said it’d be cheaper to buy a new one than to get it fixed but does anyone know how to fix this or what exactly is wrong with it?