I have the same issue. I have 4 tvs and 4 Roku devices. And just purchased a Tablo 4th Gen 4-Tuner Over-The-Air (OTA) DVR
I have (2) Roku Express model 3960X devices that do not work no matter what tv I place them on. Tried everything, factory reset, reboot router, etc, etc.
However it does work on these Roku devices no matter what tv i place them.
Roku Streaming Stick 3810X - seems to work so far
Roku Express 3930X - seems to work so far
I have a Verizon network.
I am very disappointed, not sure what the issue is but they should spend more on quality assurance and testing then on advertising.