First, try unplugging the device for a minute, then restarting it. Does that work?
If not, Settings > Network will take you to an area where you can reset the network connections. Naturally, you need a remote, so have that handy (app won't do for this). After you reset the network connections, it will have to go through the connection process again.
DBDukes Roku Community Streaming Expert Note: I am not a Roku employee.
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