Just for all the posters here. It IS the TV.
I eliminated WiFi, hardwiring my TV with a USB dongle, same issue.
I have a newer TCL TV running a newer firmware 5' away that works fine with Spectrum. I ended up just using a Roku streaming stick on my TCL TV versus the embedded Roku. The stick works perfectly.
This is something to do with TCL, Roku and firmware 8.1.0 4140