No need to provide all the details - I read a post from 7 months ago and zeroed in on the solution - it’s all about ad blocking. I run a Ubiquiti Unifi home network where the gateway implements network-wide ad blocking, so I turned it off, reset the Roku Ultra, and it miraculously Paramount+ started working.
Was I happy with this? Heck no! Why should I have have to disable a major beneficial feature of the Unifi network in order to get one app to work? That’s major league BS!
So what did I do to get round the issue? I used the Unifi traffic logging functions to analyze which domains were being blocked by Unifi whenever the Roku accesses the Paramount app, and to my disgust, dismay and disappointment, there are no fewer than 15 advertising domains that are accessed by Roku and/or Paramount before it will get around to streaming the video we all pay for. I then re-enabled system wide ad blocking, but added these 15 domains as ‘allowed’ in the firewall rules. It now works, but boy does this grind my gears.
Evidently a recent firmware update added a new advertising domain that it considers ‘mandatory’ and bricked Paramount+. I don’t know at this point if this can laid at the door of Roku or Paramount, but whoever it is, it feels pretty sleazy.