But it worked. My internet service is back up.
I work in customer support, so I know firsthand that things that shouldn't break do, and things that have no business working work, but I didn't do anything to my computer that should have made a difference, yet here we are.
Since the built-in ethernet connection wasn't working, I slipped the ethernet card from my old computer into the new one. After an hour of tinkering with no success, I pulled out the card and rebooted. As soon as I enabled the on-board port, my internet connection was restored. That's right, all I did was put in a card that I really didn't think would help, then removed it. And it fixed the connection.
I'm so excited by this development that, after I post this on the blog, I'm not going to do anything that might make the connection break.
I didn't hear from the cycle shop today so I don't know how lucky I am overall, but at this moment, things are looking up.
Shhhh. Don't jinx it.