@AnnieB1
It is possible to use a mobile hotspot to stream to your Roku device, although streaming can burnn through a lot of data and use your hotspot allowance (if limited) quite quickly.
When the internet service is down, usually a good time to switch over to antenna TV and watch free over-the air programs through the antenna or pop in a DVD. I have heard some people also still read books.
If you want to try for the hotspot though, here are some simple instructions from Apple support.
https://support.apple.com/en-us/HT204023
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
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