Have rokus and Roku TV's. Netflix, Amazon , YouTube tv and Plex steam perfectly in every room.
Use the Spectrum choice app and it's blocky, freezes and looks horrible, who is the Spectrum service so bad?
Will it improve our an I wasting my money, please help!
How are these devices connected to your LAN? Ethernet? WiFi?
How many wireless devices are being used on your LAN?
What is your internet speed? What does a speed test show you get?
Post your modem signal levels so we can advise if troubleshooting noise in your drop is causing slow speeds, which will cause the issues you describe.
I have ELP internet (3d/1u), and I have no issues using the Spectrum app on my secondary TV sets.
I cannot say why the other OTT/streaming services work well, but the Spectrum App does not, and I honestly missed that in your original post.
We are peers, and can't help with the app itself, only the infrastructure that allows you to connect to the app.
If you eliminate all the other possibilities (bad wires, noise, Cell phone interference, etc.) then whatever is left must be the problem... I assume that anyone you call is going to ask you to check what I've suggested first, before escalating the issue.