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Please note that you have the option to use the mobile app in replacement of your remote, your TV must be connected to the WiFi network you can use a Roku mobile app from your phone. The Roku mobile app will work only when the Roku TV and the phone are connected to the same WiFi network.
Here's a link to our support page to find out more about the feature: How to connect the Roku® mobile app to your Roku device over Wi-Fi®
However, if there's any changes on the network (SSID and password), you will need a physical remote in order to input your new password and connect to a new wireless network. For US customers, you can check out replacement remotes in our accessories store here
Hope this helps! Let us know if you have any other concerns.