Roku continues to have RLP-999 issues and they can’t give you an estimated time of repair. I have tried everything to get the spectrum app running on two out of our 5 TVs to no avail. It makes no sense that the app works on some TVs and not others.
RLP-999 is a Spectrum error and not Roku. I know that Spectrum has been having some issues lately (no surprise with Spectrum) and some specific issues with their Roku app and streaming.
You would need to reach out to Spectrum technical support directly.
I also suggest unplugging the modem/router and Roku device for a couple of minutes and see if that helps, but if not reach out to Spectrum as they may need to do a remote reset of your service.
Please recognize that this is Spectrum's app, adapted to run on the Roku TV operating system, and supplied to Roku. They could have created slightly different versions for different makes of Roku TV, or even specialized builds for individual TV models. Roku is just the platform on which they run.
On each TV, highlight the Spectrum app on the set's Roku channel grid and press the * key on the remote. Make note of each app's version and build number to see if they relate to which sets have the problem. This information could be helpful to Spectrum in tracking down their problem.