YoutubeTv stopped working. AT&T fiber internet. Samsung smart TV.

I have a Samsung s90c smart TV and I’m using Samsung’s YoubeTV app on at&t internet.  YouTubeTv worked fine until January 29 and then it stopped loading channels/videos.  Everything else on the TV works fine. 

I have no problem with Samsung’s apps for Youtube, Prime, FrndlyTV, MAX, Pluto or Tubi.   I have spoken to Samsung and they have remoted into my TV and tell me it’s not a TV problem.  He suggested changing DNS settings to all 8’s.  I have done both soft resets (holding down the power button for 15 seconds, unplugging TV for 30 seconds) and hard resetting the TV to factory settings.  I have reset the SmartHub.  I have also deleted the YouTubeTV app and reinstalled it multiple times.  I have deleted/reinstalled the app along with the various resets in about every combination I can come up with.  The firmware is up to date.  This is the second S90C I have had since my initial purchase in early December 2023.  The first one intermittently turned itself off and back on (and Samsung couldn’t remotely repair it) so I returned it a week and a half before the YoutubeTV problem started.  The YoutubeTV app worked fine on both of them until now. 

The YoutubeTV app will start and I can go to the homepage or live TV page with guide.  This was problematic until I turned off the autorun in settings.  If I click on any video thumbnail or guide channel on either page, the video/channel will not load; I only get black screen with circle loading bar.   I have spoken to Youtube and they don’t have a solution.  My location is correct in YoutubeTV.   I am not attempting to run YoutubeTV on more than three devices at a time.    I am not a 4K subscriber.  I have decreased broadcast delay.  I have lowered the resolution to 720p.  I have gone into the app and deleted cache and data (However, there has never been a numerical amount of cache or data.  Only zeros.).

My internet provider is AT&T fiber.  I’ve had gigabite service for years.  Speedtest on the TV browser has measured no lower than 30 Mbps download/40 Mbps upload in tests at different times/different days.  I know that seems low;  today, I got 117 Mbps/189 Mbps wireless and 98 Mbps/72 Mbps wired.  I have tried connections both with wifi and network cable.  My at&t app suggested that I create a guest network and attach the TV to it.  I did.  I   have a friend who services computer networks and he opened a couple of ports on the router/gateway that he said I needed opened.  He also reset the router/gateway.  I spent some phone time with AT&T rep and he could find no problem with my service or equipment.  He also reset the router/gateway.  He also said that since I can run YoutubeTV videos/shows on my laptop, then the at&t network is not blocking youtubeTV.

I have a Roku plugged into the back of this TV and it works fine.  I can (and am) watching YoutubeTV on it.  I’d really like to watch it on my new TV though.  Does anyone think this might be an at&t issue?  Anyone seen anything like this before?