Had the same problem. After trying all the above solutions, my last solution worked.
Solution:
1. Open the ROKU Spectrum channel
2. Go to Settings top right Gear.
3. Go to Sign Out and sign out.
4. Now select Sign in Automatically.
Thats it. I only did this on one of the seven Roku Streaming Sticks which fixed all of them.
I tried the Roku System Restart as instructed on the screen as well as trying powering off/off the Spectrum modem/Roku Ultra devices, and signing out/in my Spectrum account on the App to no avail. What finally did work for me was to select the Spectrum App and restart the App via the * button on the Roku remote.
What **bleep**! Roku blames Spectrum. Spectrum blames Roku. Why can’t or won’t you guys fix this persistent and pervasive problem? Neither of you give a **bleep** about your customers. My choices are limited for streaming TV. I just wasted hundreds of dollars on two Roku TVs as they won’t connect to Spectrum just as all these folks describe.
Nope.
Nope.
I have a inexpensive Roku TV and have had the same issue as everyone posting. This a TV that Sprectrum is streamed to from the app. I tried everything that has been posted and nada. My other two tvs are using the cable and spectrum works fine. I even factory reset my tv