Just bought a new Roku Streaming Stick Plus. Out of the box it connected to my iPhone XR’s hotspot without issue. After the Roku updated it’s software and rebooted, it will no longer connect to the mobile hotspot. It connects to other Wifi networks without issue.
In my limited knowledge and research, it appears that perhaps the DFS channels that the iPhone broadcasts on do not play nice with the Roku. This is odd since pre-software update things worked fine.