I have a Samsung Galaxy S20 and a Roku Streaming Stick+ and I just figured out how to screen mirror on my tv. However, I can't figure out how to get the audio on my phone to play through my tv. Is this even possible? I tried using the Roku app but it doesn't put the sound on my tv, just through my phone and a connected bluetooth device. I do not have a Roku tv and my tv is not a smart tv. It's just a generic flat screen tv. Any help would be appreciated!
I win! It's not a ROKU problem. I now have HD video mirroring with audio to ROKU from Samsung S20 using either SmartView or DEX (proprietary Samsung software for Android, nee Miracast). This required 2 solid hours of Samsung tech line chat and several reboots.
First open smartview and connect to ROKU then open SmartThings settings to send audio to Roku. Verify that none of your devices (TV, ROKU, phone) are muted. Test with any video app you should have sound and audio from your TV.
Dex is different. It provides a MacOS or Windows10 desktop. You will need to adjust your TV picture settings to see the full screen. Then you use the Samsung TouchPad app to control an on screen cursor. In the lower left corner clicking on the checkerboard pattern opens your Android app icon folders and you can open the app you want to cast to ROKU.