We're currently Uverse customers at about 54mbps max speed (we don't have high demands). We use the (required?) modem/router combo supplied by AT&T. Our house in long and with a lot of interceding ...
Your router comes with these two features that can put your network at risk, enabled by default.
I don't have U-Verse but I'm thinking you should be able to switch their equipment to a 'pass through/bridge' mode to where it should just act like a modem at which point it should just pass traffic ...