Called the tech support for my ISP the second they opened this morning.
Wasn't the tower.
Got into my router settings - the one that said "Does your internet connection require a login?" was unchecked. My ISP requires a PPPoE connection with a password. Tech guy said sometimes a power surge can reset settings (which I did not know) but not reset the entire thing (I hadn't thought of this because the SSID was the same and the password hadn't been reset).

Fixed in under 10 minutes. Embarrassed but I learned something new. And I got outside to do things and possibly got my first heatstroke of the summer. Yay!