FYI: Good news. Since I first posted I was having problems, I have only had a problem a coupla times, and both those have been appeared to be outages closer to home and lasted only seconds. So short that even though I had a screen
up with the tracert command ready, one time the problem was gone by the time I ran it. The other time it was a problem just a coupla hops from me, but when I went back to the browser to refresh, it was already working again. Before the frequency was every few hours and lasted at least 30 seconds.
In other words, I haven't had the original symptoms I reported in several days.