Thanks, Aljo. Immediately after I posted my previous message on the forum, I went on to have a flawless connection to EA servers for the next 5-6 hours straight. It was awesome! Every morning for the last few days, though, between around 2:00 AM and 6:00 AM Central time, I've been having terrible connectivity issues and getting stuck on the "Searching" screen in World of Chel 6's Drop-In during matchmaking.
It's conceivable that my ISP could be throttling bandwidth in the middle of the night, however, I don't experience connectivity issues with my other games or the Playstation Network, outside of NHL 23. Nothing about my physical internet connection changes from day to day -- it's a wired connection that achieves a maximum speed of 300 Mbps.
The only thing I've noticed is that there are times when the game will freeze up during a search, or before the opening faceoff, at which point I may close and restart the game if it doesn't recover. The matchmaking searches that I try after one of those forced restarts seem like the ones that are most vulnerable to the issue of failing to find an opponent. From the outside looking in, it almost seems like the act of restarting the game fails to clear away some junk data that interferes with my matchmaking searches for a while. The issue eventually resolves itself after a long time spent starting and restarting my console and the game, so that I am able to find matches again in 6's Drop-In after repeatedly "Searching" for an hour or two.