I had the same issue. Disabling my VPN allowed me to stream via browser (https://therokuchannel.roku.com) as well as with the Roku desktop/laptop app on Windows 10.
Don't know if this applies to your situation but, it worked in mine. Many website servers block certain IP addresses despite being on a legitimate VPN.
Thank you that worked I had tried a few other steps.
I am also getting this error, if I turn off my VPN, I can stream what I want to watch. I hope that they have a solution to this error.
Glad you're able to work around this issue. I should clarify two points: 1) this is NOT entirely a Roku issue but rather a VPN issue as well; 2) I only need to disable my VPN to establish the connection - once streaming begins, I re-enable my VPN without further issue. Both points pertain to not only Roku, but also many websites.
I am using the app and the Edge browser on my computer and have the same issue. The tv's and phone work fine.