Which gateway do you have? Mine is the 3801HGV, and it stays up and fast 24/7/365. I have heard that the 3800 had issues, but I've never had that gateway. I have noticed that the 3801 does not like my HD2's WIFI at times though, and I've had to force it to connect to it.
I have had the Uverse TV box hang up on me 3 times though (over 1.5 years), and had to reboot it - manually by unplugging it.

Oh, and I am barely under 18,000 ft from the CO, with no remote in-between - last house on the line, literally. BTW - my DSL was ok, but the Uverse has been much more stable, and faster. My POTS service sucked royally for over a decade though, until I went with DSL, and I have seen continual improvements from AT&T since then. Before they sold Uverse here, they had to go and clean and reconnect every single line terminal on the street (we are still on poles here, not buried cable).

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I had no issues with DirecTV service, but their billing and CS departments were awful, so I left.