Unfortunately, I do not know how to determine that. What I have observed since posting, though, is that the Roku says it is “not connected” to the network. So I believe that must be the problem. Following a recent update, the Rokus will not complete the setup connection to the network unless they can also connect to the internet. I’ve posted on the Roku support community forum about this.
In case the Roku folks don’t correct this bug in their update, does anyone have a recommendation for a different platform? (Fire -vs- Apple?)