I'm having the same/similar issue w/my TCL Roku TV. Screen mirroring was working fine a few weeks ago and now can't be seen by any device. The remote feature in the mobile app was working fine this morning and now it won't connect to this TV anymore. Both screen mirroring and the mobile app/remote work fine with all the other Roku's in my house so there is definitely something peculiar to the Roku TV. Did a recent update introduce a bug?
Update: performing a System Restart from the Settings menu seems to have done the trick. I had tried powering on/off and unplugging the TV to reboot which didn't work but the Restart got it to reconnect.
Mine just started telling me to wake my tv then connect except my tv was on. Fix was simple although annoying and since Roku claims app to be free they never have to offer any solutions. Anyways turn your iOS WiFi button off and wait 15 seconds. Turn it back on and connect to network and then it should work. Hope this helps.
Same issue here. The only way I can get the app to connect to the device (TV) is by actually unplugging the TV. Hopefully ROKU will address this issue because it's extremely annoying and unplugging the TV every time I want to use the app is not an option.
I've had this issue appear twice on my Roku TV. Both times I unplugged the WIFI extension router that it's wirelessly connected to for about 20 seconds. Once the router booted back up it was fixed. Rebooting my main router did not fix the issue, it had to be the extension that reaches the TV. Also, the only thing that has fixed a similar issue I have where the TV stops seeing my DLNA server is to unplug the TV for about 20 seconds then plug it back in. So, I think that's worth a try too for problems like this.