Good grief. My AT&T DSL connection died. Again. Talk about tiresome.
I spoke to an AT&T tech service rep on the telephone. To be fair, I really have to give this guy credit. Instead of making me jump through a whole bunch of useless hoops, he addressed my problem promptly and efficiently. He noted that there had been a group outage that caused my previous problem, but correctly figured out that there must be something wrong with my specific hardware -- that is, the card that connected to my modem. So he issued a service ticket, telling another technician to replace the card.
That seems to have fixed the problem. We'll see.
I like his approach. During a previous call, I complained about intermittent network outages. The rep who answered my call said, "Well, you have network connectivity right now. We can't do anything unless you call while the network is down." As it turns out though, that was not strictly true. As it turns out, they could have replaced the card in question to see if this prevented my intermittent outages from occurring.
Here's hoping that this latest fix does the trick.