I was gifted a Roku Ultra a few months back and finally got around to setting it up. Each time I try to sign in to Plex using either my user name or email it tells me that it couldn't authenticate the user. I have an Nvidia Shield Pro in another location and Plex works fine there. As well I am still able to connect to the web app on my computer and using the app on my phone.
I could desperately use some suggestions.
TIA
The Plex webapp also seems to recognize that the Roku Ultra exists, but tells me I can't stream content to the connected player when I try to cast to it. This works on the Shield.