Hi, @Conradkoch.
Thanks for sharing this here in the Roku Community!
We appreciate you letting us know you're experiencing an issue casting your Nixplay frame to your Roku, and we'd like to be able to help.
Have you tried checking if your Nixplay device and Roku are both connected to the same network? To check this on your Roku device, just head over to Settings > System > About.
You may also visit this support article: How to screen mirror from your phone, tablet, or computer to your Roku streaming device.
Please let us know if you need more help.
Best,
Emman
Emmanuel-D.
Roku Community Moderator