Thanks for reaching out, @Nils_Hannaas!
So we can better assist you, please provide a brief description of your current setup using this link as a guide.
Make sure to describe your network configuration/topology, including any networking hardware currently in use, so we can have a clear understanding of how your devices are communicating.
Does this behavior occur for all Displays? If you use a Web Display or a different Chromecast device does that update as expected?
Thanks!