Roku might have lost connection to the Wi-Fi network. To check whether this is the case, go to the Settings option on your Roku and scroll down to the Network option. Check whether your Roku device is connected by selecting the Check Connection option. If the issue is with your router, set it right. If your router is working correctly but Netflix isn’t working, proceed to the next step for Netflix Streaming Error.
Check whether the Roku device has the latest updates installed. Go to the Settings application, choose System, and then click on the Software Update option. Choose the Check Now option and find whether there are Netflix updates available.
Most of the time, a simple restart clears issues and this is true for Roku as well. Unplug the Roku device, and let it be idle for 10 seconds. Plug the Roku cable into the Roku device and wait for a minute. Then, launch Netflix on your Roku TV.