I'm having the exact same issue here with my Samsung RU7100 TV:
"Unable to turn on Samsung TV via google home, while SmartThings is able to do it - Google Nest Community" https://support.google.com/googlenest/thread/42071215/unable-to-turn-on-samsung-tv-via-google-home-w...
I've got the latest firmware - from August on both my smart things app and TV. I can even turn on the TV via the ST app when it shows offline.
I've factory reset everything, even confirmed my DNS is set to Google, everything is on wifi and I even setup email alerts on my unifi AP if any device were to disconnect from the network.
I've even tried removing the TV from ST after factory resetting it and deleting my home in google home and setting everything up again including reconnecting smart things in GH. I've even split my wifi bands so my nest and TV are on 2.4ghz while my laptop is in 5ghz
I also have the same problem with the google assistant so it's not just the home or nest.
Any other ideas I'd appreciate it?
Hey there Rm09,
I'm sorry about the delayed response, I appreciate your patience! Are you still experiencing this issue? If so, I'd be happy to look into this.
Now, looking at the information in the old thread, it seems like there is an assortment of people with this issue with different fixes. However, I would suggest that you check out this article from Samsung on How to Setup Google Home as well as Google Failed to Discover TV, as they would be the most related. If they aren't able to solve the issue, I would suggest that you reach out to Samsung support to see if they have any more resources or fixes available.
I'm sorry I wasn't able to help more, but if you had any other questions or concerns, please let me know!