Why this answer matters
USB-C describes the connector, not the capabilities of every cable, hub or display. A charge-only or non-video cable can charge the phone while failing completely for a monitor connection.
3 requirements4 verification steps1 primary source
Requirements
What has to be true
- A USB-C display or adapter path that supports DisplayPort video.
- A cable rated for the video path you are using; a charging-only cable is not enough.
- A monitor input and resolution/refresh combination supported by the full phone-cable-adapter-display chain.
Verify it yourself
Use this test sequence
Change one variable at a time so you know which requirement made the difference.
- 1
Connect directly to the display when possible to remove the dock/hub as a variable.
- 2
Confirm the display is on the correct input.
- 3
Try a cable explicitly specified for video/DisplayPort rather than assuming every USB-C cable carries video.
- 4
If another device works with the same display and cable, test the iPhone with a different known-good video adapter or cable.
Limits
What this answer does not prove
- The browser cannot inspect the phone-to-display DisplayPort negotiation from another device.
- USB data speed, charging power and display support are separate USB-C capabilities.
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