Hi @horus66,
Thank you for posting here in the Roku Community!
We understand you are having trouble screen mirroring your Samsung through your Roku device/TV. We're happy to help.
Please try the troubleshooting steps below:
1 Go to Settings > Advanced system settings > Network connection reset > Reset connection.
2. Restart your router/modem and then try to reconnect your device.
3. Restart your Roku device from the Settings menu by navigating to Settings > System > Power > System restart. You can skip this part if you don't see a Power submenu.
Also, restart the device you're trying to mirror from.
Let us know if this works for you!
Best,
The Roku Community Team
John
Roku Community Moderator