Wow! This thread has been an eye-opener! This is my first time in the community. I was about to go nuts figuring out what happened between the time I turned off my TV Sunday night and when I turned it back on Monday evening. My Ultra had worked flawlessly for almost three years until then.
Spectrum is my ISP and I also have their streaming service, which was the only thing I could watch until this evening. Multiple restarts of my Roku and reboots of modem and router. Still got an error that I wasn't connected to the Internet - whether the wired or wireless connection - though the About in settings said I was connected. Spectrum ended up sending out a tech and he couldn't figure it out, but he was able to determine that the problem wasn't on their end.
Something I read here prompted me to go into the router settings. Ultimately, the only thing I changed was to have a static address and to select DNS automatically. Now everything is working fine. The only correlation I can come up with is that I stopped using a proxy server I was paying for and they took my IP address out of their system.