Roku TV Incompatible with Xfinity Cable

This is a caution to those who want the convenience of a Roku TV for streaming, but also want to view their Xfinity cable channels on that TV.  In my case, it doesn't work.

There appears to be a fundamental issue, one of compatibility, between the Xfinity cable signal, and Roku streaming devices, including the Roku TV.  It is not a universal problem, but a geographic one, where the devices and cable signals may be perfectly fine in one area, but a few miles away, they are not.  Here is my current experience:

For years, I used Roku boxes to stream to my various TVs without any issue.  Typically, cable entered the TV via HDMI 1, and Roku via HDMI2.  I also had soundbars, wireless woofers, on one setup an HDMI switch to accommodate additional inputs.  Everything worked great.   One month ago, I moved across town, about 3 miles.

I set up exactly the same hardware in the same configurations.  Xfinity cable worked perfectly.  But Roku streaming did not.  Some channels would stream --- YouTube being the most well known --- but pay services like Amazon and Netflix would not.  One could start watching those, but within a few minutes, streaming would stop and various error messages would present themselves.  Xfinity suggested I replace my Xfinity box as mine was several years old, which I did.  Nothing changed.  I needed to replace my main TV after the move as the new house could not accommodate the 65" Visio that worked at the old house, so I thought I might cure the streaming issue by buying a 55" Roku.  The Roku TV will not show Xfinity cable.  However, after installing the Roku TV, I decided to see if a Roku Ultra would stream to a different TV in another room, and that worked.  The puzzle grows.

I spent considerable time AI chatting on the Roku customer support website, finally got hooked up with a human.  The human eventually referred me to a special team, and that special team referred me to another special team.  After an hour of chatting, someone from Roku admitted the problem I was experiencing was a known issue with "the cable channels."  Finally, I was assured "the engineers" would solve my problem TODAY (that was yesterday).  The problem remains.   In a few hours, I am going to attempt to see if I can determine the status of my "Roku Issue ID" (4H-270-445).  I'm guessing the chatbot will be baffled; I'll repack my Roku TV and return it.   Perhaps a different TV with a new Ultra will work.  Who knows?