I have an Express+ and I have been trying to mirror my Laptop (Google or Firefox) to the Roku. It doesn't seem to find anything. Under devices, it says "none" and a message under that saying always blocked devices. Why would it say that, if the feature is available. Any idea if this feature will work? I have cast my Laptop and Chromebook via the Chromecast easily, but with the Roku, so far no luck. Thanks for any advise.
Depending on the model of Express+ you own, screen mirroring may not be supported. Model 3710 does not support the feature. If you're using model 3910, the feature is only supported i the device is connected to your TV via an HDMI cable.