Perhaps too exciting of an afternoon. The Frontier tech showed up at my mother's place to try and figure out why her Internet connection was going down every five minutes for 15-30 seconds. According to the tech, their network monitoring center saw no signs of any problems with the line or the connection. Therefore, it must be software. While I was talking to him on the phone, he suddenly said, "Wait a minute. Why did the modem [by which he meant the CPE box that converts DSL to LAN] just go off?" Sure enough--the new CPE box they installed a few months back was periodically shutting down, then coming back to life.
1. What kind of networking monitoring center can't figure out that the far end of their DSL connection is shutting down for 15-30 seconds on a regular basis? Even without any active failure, you would expect a series of packets that don't get a response from the far end would set up some sort of alarm...unless they have decided that customers shut off CPE often enough to suppress such alarms.
2. The nice thing is that the new CPE is not only reliable, but produces a much clearer image when using Skype with my mother. My guess is that whatever was causing the CPE to fail was also interfering with reliable packet transmission, causing Skype to create much lossier compression, and not just when it was shutting down.