Hello Oliver0208,
It sounds like you are having trouble streaming Netflix and other media apps from your iPhone to a projector. Check out this link for support with using the adapters for iPhone.
About Apple Digital AV Adapters for iPhone, iPad, and iPod touch
Find out what to do when you have the following issues.
Make sure that you're using a Digital AV adapter (which has an HDMI port). If you're using a VGA adapter, it doesn't carry audio signals. To hear audio with a VGA adapter, you need to connect to the headset jack on your TV, monitor, projector, or stereo.
The app might not be compatible with your adapter. Check compatibility on the app's info page in the App Store or contact the developer."
Cheers!